General Considerations and Maternal Evaluation
BS. Nguyễn Hồng Anh
Pregnant women are susceptible to any meical an surgical
disorder that can aect women of childbearing age. Chronic
illnesses oten precee pregnancy, an an acute conition can
complicate an otherwise normal pregnancy. Both chronic an
acute disorders raise the risk for antepartum hospitalization.
Approximately 10 per 100 pregnant women incur an antepartum amission, an one thir are or nonobstetrical con-
itions that inclue renal, pulmonary, an inectious iseases
(Gazmararian, 2002). Te hospitalization rate ue to trauma
approximates 4 amissions per 1000 eliveries (Kuo, 2007).
Tose with intellectual an evelopmental isabilities have a
higher incience o hospitalization (Mitra, 2018). Last, 1 to
2 percent o pregnant women will unergo a nonobstetrical
surgical proceure (olcher, 2018).
Obstetricians should have a working knowledge of the
wie-ranging meical isorers common to chilbearing-age
women. Many o these are within the purview o the general
obstetrician. Other isorers, however, will warrant consultation with specialists in maternal-etal meicine, an still others require a multiisciplinary team. Te latter may inclue internists an meical subspecialists, surgeons, an anesthesiologists (Levine, 2016). Te Society or Maternal-Fetal Meicine
(2014) has reene aspects o maternal care an propose
conitions requiring specialize care.
reatment shoul never be withhel because a woman is
pregnant. o ensure this an allow or iniviualize care, several questions must be aresse:
• What management would be recommended if the woman
were not pregnant?
• If the proposed management is dierent because the woman
is pregnant, can this be justie?
• What are the risks and benets to the mother and her fetus,
an are they counter to each other?
• Can an individualized management plan be devised that balances risks versus benets?
MATERNAL PHYSIOLOGY AND
LABORATORY VALUES
Pregnancy inuces physiological changes in virtually all organ
systems. Many of these are discussed in Chapter 4 and in the
subsequent chapters in this section. In turn, numerous laboratory test results also are normally altere. Some values woul be
considered abnormal in the nonpregnant woman. Conversely,
some may appear to be within a normal range but are eci-
ely abnormal or the gravia. Tese changes may complicate
the evaluation o coexisting conitions. o ai interpretation,
normal laboratory values in pregnancy are liste in the Appen-
ix (p. 1227).
MEDICATIONS
Fortunately, most meications neee to treat requently
encountere illnesses in pregnancy can be given with relative saety (Briggs, 2017). Tat sai, notable exceptions are
considered in Chapter 8 and throughout this text. e risks
an benets o meication use uring pregnancy an lactation
are outline in rug labels using the Pregnancy an Lactation
Labeling Rule (PLLR) requirement rom the U.S. Foo an
Drug Aministration (FDA).
NONOBSTETRICAL SURGERY
Te chances o averse maternal an perinatal outcomes ollowing nonobstetrical surgery uring pregnancy are relatively
low and cannot be separated from risks of the underlying condition (Balinskaite, 2017). However, risks are likely greater
with complications. Compared with simple appendicitis, per-
orate appenicitis with eculent peritonitis has signicantly
higher maternal an perinatal morbiity an mortality rates
even i surgical an anesthetic techniques are awless. Moreover, procedure-related complications may adversely aect outcomes. For example, a woman who has uncomplicate removal
of an inamed appendix may suer aspiration of acidic gastric
contents uring tracheal intubation or extubation.
■ Maternal Morbidity
Te most requent nonobstetrical surgical proceures per-
orme uring pregnancy are appenectomy, cholecystectomy,
an anexal surgery (Vujic, 2019; Yu, 2018). Postoperative
complications in nonpregnant patients can similarly harm
gravid women. However, data comparing these complications in these two groups are conicting. Te National Surgical Quality Improvement Program showed that morbidity
and mortality rates from nonobstetrical surgery did not dier
between pregnant and nonpregnant women (Moore, 2015). In
a aiwanese cohort o nearly 5600 gravias, the inectious postoperative complication rate was slightly higher an the mortality rate was ourol greater than those rates in nonpregnant
women (Huang, 2016).
Te reporte postoperative complication rate in gravias
approximates 5 percent, an the maternal mortality rate in
these cases is <1 percent (Huang, 2016; Vujic, 2019). Moreover, preoperative inection, specically sepsis, is associate
with a higher risk of maternal death (Erekson, 2012).
■ Perinatal Morbidity
Excessive perinatal morbidity associated with nonobstetrical surgery is also attributable in many cases to the isease
itsel rather than to surgery an anesthesia. wo- to threefold elevated risks for spontaneous abortion, preterm delivery,
preeclampsia, an cesarean elivery have been reporte (Yu,
2018). Balinskaite and associates (2017) identied a greater
risk of fetal death, preterm birth, fetal-growth restriction, and
cesarean elivery in 47,628 women unergoing nonobstetrical surgery. Most o these complications evelope in cases
perorme emergently (Vujic, 2019). Te Sweish Birth Registry provies valuable ata comparing perinatal outcomes in
women unergoing surgery with those o the general obstetrical population (Table 49-1) (Mazze, 1989). Te inciences o
congenital malormations an stillbirth were not signicantly
dierent from those of nonexposed newborns. However, inci-
ences o low birthweight, preterm birth, an neonatal eath
were signicantly higher. Increased neonatal death rates were
largely ue to prematurity.
Fetal abnormality rates are not associate with maternal surgery in early pregnancy. Källén an Mazze (1990) reporte a
nonsignicant relationship between elevate neural-tube eect
rates and operations performed at 4 to 5 weeks’ gestation. A
large atabase stuy oun no evience that anesthetic agents
were teratogenic (Czeizel, 1998). According to Briggs and
coworkers (2017), most inhalation anesthetic agents appear
sae.
More recently, concerns o neuroevelopmental harm with
the use o anesthetics or obstetrical or etal surgery have been
raised. In 2016, the FDA issued a warning regarding impaired
brain evelopment in chilren ollowing in utero exposure to
inhale isourane, sevourane, an esurane as well as intravenous propofol and midazolam. Such risks appear to accrue
ater 3 hours or more o exposure (Olutoye, 2018).
LAPAROSCOPIC SURGERY
In the rst trimester, laparoscopy is the most common
proceure use or iagnosis an management o several
surgical disorders. In 2017, the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) updated its recommenations concerning laparoscopy use in pregnant women
(Table 49-2) (Pearl, 2017).
For pregnancy in general, laparotomy also is common. One
5-year stuy o almost 1300 pregnant women reporte that
open appenectomy was perorme in 36 percent o 857 gravi-
as compare with only 17 percent o nonpregnant patients.
O those unergoing cholecystectomy, an open approach was
use in 10 percent o 436 pregnant women compare with 5
percent of nonpregnant women (Silvestri, 2011). In a study
rom Japan, Shigemi an colleagues (2019) escribe 6018
pregnant women unergoing abominal surgery—4047
by laparotomy an 1971 by laparoscopy. Operative times,
hospital stay lengths, an rates o averse etal events an
bloo transusion were all greater in the laparotomy group
(Table 49-3). Others instea report equally satisactory outcomes
with either approach (Cox, 2016; Lee, 2019). Randomized
TABLE 49-1. Birth Outcomes in 5405 Pregnant Women
Medical and Surgical Complications
trials to compare benets and risks of laparoscopy versus laparotomy uring pregnancy are neee, but implementation
seems uneasible (Bunyavejchevin, 2013; Lee, 2019).
For anexal mass surgery in pregnancy, laparoscopy is preferred, and several studies conrm its relative safety (Daykan,
2016; Webb, 2015). In addition, laparoscopic splenectomy,
arenalectomy, an nephrectomy also have been escribe in
pregnant women (Asizare, 2014; Dong, 2014; Miller, 2012).
When rst used, 26 to 28 weeks became the upper
gestational-age limit recommended. However, as experience
has accrue, many now escribe laparoscopic surgery performed in the third trimester (Shigemi, 2019). In one report,
a thir o gravias unergoing laparoscopic cholecystectomy
or appenectomy were >26 weeks’ gestation (Rollins, 2004).
No serious adverse sequelae are linked to these procedures, and
laparoscopy can saely be perorme in all trimesters.
■ Hemodynamic Effects
Precise eects of laparoscopy in the human fetus are unknown,
but animal investigations are inormative. During laparoscopy, require abominal insuation causes hemoynamic
changes that are summarize in Table 49-4. Reey an associates (1995) stuie baboons at the human equivalent o 22 to
26 weeks’ gestation. No substantive physiological changes were
found with insuation pressures of 10 mm Hg, but 20 mm
Hg caused signicant maternal cardiovascular and respiratory
changes ater 20 minutes. Tese inclue aster respiratory rate,
respiratory aciosis, iminishe cariac output, an increase
pulmonary artery and capillary wedge pressures. In pregnant
ewes, uteroplacental bloo ow eclines when intraperitoneal
insuation pressure exceeded 15 mm Hg (Barnard, 1995;
Hunter, 1995). is stemmed from decreased perfusion pressure an elevate placental vessel resistance (see able 49-4).
In women, cardiorespiratory changes are generally not severe
i insuation pressures remain <15 mm Hg. Despite maintaining these low insuation pressures in women at mipregnancy, the cariac inex roppe 26 percent ater 5 minutes
of insuation and 21 percent after 15 minutes (Steinbrook,
2001). Even so, mean arterial pressures, systemic vascular resistance, an heart rate i not change signicantly.
■ Technique
Te ollowing is an overview o laparoscopic technique in
pregnancy. For a etaile escription an illustrations reer to
Chapter 15 in Cunningham and Gilstrap’s Operative Obstetrics,
3r eition (Kho, 2017).
Preparation for laparoscopy diers little from that used for laparotomy. Bowel cleansing is not neee but may ai visualization
an manipulations by emptying the colon. Nasogastric or orogastric decompression reduces the risk of stomach trocar puncture
an aspiration. Aortocaval compression is avoie by a let-lateral
tilt of the patient’s body. Positioning of the lower extremities in
boot-type stirrups maintains access to the vagina or etal sonographic assessment or manual uterine displacement. Intrauterine
manipulators are logically avoie. Pregnancy-relate hypercoagulability combine with pneumoperitoneum- associate,
lower-extremity venous stasis raises venous thromboembolism
risks. Prophylactic pneumatic compression devices are wrapped
aroun the calves uring patient positioning.
Most reports escribe the use o general enotracheal anesthesia with monitoring of end-tidal carbon dioxide—EtCO2
(Hong, 2006; Ribic-Pucelj, 2007). With controlled ventilation,
EtCO2 is maintained between 30 and 35 mm Hg.
Beyon the rst trimester, technical moications o stan-
ar pelvic laparoscopic entry are require to avoi uterine
TABLE 49-2. Some Guidelines from the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) for
Laparoscopic Surgery in Pregnant Women
Indications—same as for nonpregnant women
Investigation of acute abdominal processes
Excision of an adnexal mass
Appendectomy, cholecystectomy, nephrectomy, adrenalectomy, splenectomy
Technique
Position: lateral recumbent
Entry: open Hasson technique, careful Veress needle, or optical trocar; fundal height may alter insertion site selection
Secondary trocars: direct visualization for placement; gravid uterus may alter insertion site selection
CO2 insufflation pressures: 10–15 mm Hg
Monitoring: capnography intraoperatively, FHR assessment pre- and postoperatively
Perioperative pneumatic compression devices and early postoperative ambulation
CO2 = carbon dioxide; FHR = fetal heart rate.
TABLE 49-3. Comparative Outcomes in Pregnant
Women Undergoing Abdominal Surgery
puncture or laceration (Fig. 49-1). Many recommen open
entry techniques to avoi perorations o the uterus, pelvic
vessels, and adnexa. With the method described by Hasson
(1971, 1974), the abomen is incise at or above the umbilicus, an the peritoneal cavity entere uner irect visualization
(Fig. 49-2). At this point, the cannula is connecte to the
insuation system, and a 12–mm Hg pneumoperitoneum is
create. Te initial insuation shoul be conucte slowly
to allow or prompt assessment an reversal o any untowar
pressure-related eects. Gas leakage around the cannula is managed by tightening the surrounding skin with a towel clamp.
Insertion of secondary trocars into the abdomen is most safely
perorme uner irect laparoscopic viewing. Single-port surgery also has been escribe (Dursun, 2013).
In more advanced pregnancies, direct entry through a left
upper quarant port in the miclavicular line, 2 cm beneath
the costal margin, may better avoid the fundus (Donkervoort,
2011; Stepp, 2004). Known as the Palmer point, this entry site
is also use in gynecological laparoscopy because visceroparietal
ahesions inrequently orm here (Vilos, 2007).
Gasless laparoscopy is a less commonly selecte alternative
approach that uses a ro with intraabominal an-blae-shape
FIGURE 49-1 Pregnant uterus at 10, 20, and 36 weeks’ gestation depicting distortion of other intraperitoneal organs. (Reproduced with
permission from Kho KA: Diagnostic and operative laparoscopy. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and
Gilstrap’s Operative Obstetrics, 3rd ed. New York, NY: McGraw Hill; 2017.)
TABLE 49-4. Physiological Effects of CO2 Insufflation of the Peritoneal Cavity
retractors. When opened, these allow the abdominal wall to be
lifted upward. It avoids the typical laparoscopic cardiovascular
changes because abominal wall elevation is create by retraction rather than insuation (Phupong, 2007).
■ Complications
Risks inherent to any abdominal endoscopic procedure are
probably slightly greater uring pregnancy. Te obvious unique
one is peroration o the pregnant uterus with a trocar or Veress
neele (Kizer, 2011; Mala, 2014). Tat sai, reporte complications are infrequent (Choi, 2021; Koo, 2012; Post, 2019).
■ Perinatal Outcomes
Perinatal outcomes in women are limite to observational stu-
ies. Reey an colleagues (1997) use the upate Sweish
Birth Registry atabase to analyze a 20-year perio with more
than 2 million eliveries. O 2181 laparoscopic proceures,
most were perorme uring the rst trimester. Perinatal outcomes or these women were compare with those o all women
in the atabase an those unergoing open surgical proce-
ures. Tese investigators conrme the earlier nings o an
increased risk of low birthweight, preterm delivery, and fetalgrowth restriction with surgery during pregnancy. Dierences
were not oun, however, in outcomes o women unergoing
laparoscopy versus laparotomy. An observational stuy o 262
women unergoing surgery or an anexal mass note similar
nings (Koo, 2012). Although the abortion an stillbirth rates
are low with abominal surgery, laparotomy has more averse
outcomes compare with laparoscopy (see able 49-3).
RADIOGRAPHY
Imaging modalities are used as adjuncts for diagnosis and therapy
uring pregnancy. Options inclue sonography, raiography,
computed tomography (CT), and magnetic resonance (MR)
imaging. Of these, radiography is the most problematic. Inevitably, some raiographic proceures are perorme beore
recognition o early pregnancy, usually because o trauma or
serious illness (Herfel, 2018). Fortunately, most diagnostic
radiographic procedures are associated with minimal fetal risks.
However, as with medications, these procedures may lead to a
neeless therapeutic abortion because o patient or physician
anxiety or to litigation i pregnancy outcome is averse.
e American College of Radiology (ACR) has addressed
the growing concern o collective raiation oses in all els
o meicine (Amis, 2007). More recent publications have
been in support of FDA eorts to decrease radiation exposure an to reuce the number o unnecessary examinations.
Recommenations also inclue consierations or raiosensitive populations, such as chilren an pregnant or potentially
pregnant women. At our institutions, special recommenations
are mae or gravias. Raiation exposure values an uration
are recorded and monitored in high-exposure areas such as CT
an uoroscopy units. Last, consultation with the raiologist is
advised (Chansakul, 2017).
■ Ionizing Radiation
Te term radiation reers to energy transmission an thus is
applie to x-rays an also to microwaves, ultrasoun, iathermy, an raio waves. O these, x-rays an gamma rays
have short wavelengths with very high energy an are ionizing
raiation orms. Te other our energy orms have rather long
wavelengths an low energy (Brent, 2009).
Ionizing radiation can directly damage DNA or can create
free hydroxyl radicals that in turn damage DNA (Hall, 1991;
National Research Council, 1990). Methods of measuring the
eects of x-rays are summarized in Table 49-5. Te stanar
terms use areexposure(in air),dose(to tissue), anrelative efective
dose (to tissue accounting for biological eects). In the range of
FIGURE 49-2 Hasson open entry technique for laparoscopic instrument placement. A. Fascia grasped with two Allis clamps and elevated
prior to sharp incision. B. Two fascial stitches incorporate the peritoneum and fascia. C. These fascial sutures are wrapped around holders of
the Hasson cannula to anchor it in place. (Reproduced with permission from Kho KA: Diagnostic and operative laparoscopy. In Yeomans ER,
Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap’s Operative Obstetrics, 3rd ed. New York, NY: McGraw Hill; 2017.)
As note, x- an gamma-raiation at high oses can amage
DNA, and this yields two biological eects in the fetus (Brent,
2009). Tese are deterministic efects an stochastic efects.
■ Deterministic Effects
One potential harm o raiation exposure is eterministic, which
may result in abortion, growth restriction, congenital malormations, or intellectual disability. ese deterministic eects
are threshold eects, and the threshold level is the NOAEL—no
observed adverse efect level (Brent, 2009). Although controversial, the NOAEL concept supports that there is no risk below
the threshold dose of 0.05 Gy or 5 rad. It also suggests that
the threshold for gross fetal malformations is more likely to be
0.2 Gy (20 ra) (Lowe, 2020).
e deterministic eects of ionizing radiation have been
extensively stuie or cell amage that leas to isorere
embryogenesis. Tese have been assesse in animal moels as
well as in Japanese atomic bomb survivors an the Oxor Survey of Childhood Cancers (Sorahan, 1995). Other sources have
conrme prior observations an provie aitional inormation (Groen, 2012).
Animal Studies
In the mouse model, the lethality risk is highest during the
preimplantation perio, which extens up to 10 ays postconception (Kanter, 2014). Blastomere estruction cause by
chromosomal damage is the likely cause (Hall, 1991).
During organogenesis, high-ose raiation—1 Gy or 100
rad—is more likely to cause malformations and growth restriction and less likely to be lethal. Studies of brain development
suggest eects on neuronal development and a window of cortical sensitivity in early and midfetal periods. Instead, acute lowdose ionizing radiation appears to have no deleterious eects
(Howell, 2013).
Human Data
Data on adverse human eects of high-dose ionizing radiation
mostly derive from the atomic bomb survivors of Hiroshima and
Nagasaki (Greskovich, 2000; Otake, 1987). e International
Commission on Radiological Protection (2003) conrmed initial studies showing that the risk of severe intellectual disability
was greatest between 8 and 15 weeks’ gestation (Table 49-6)
(American College of Radiology, 2018). e mean decrease in
intelligence quotient (IQ) scores was 25 points per Gy or 100
ra. Te ose response appears linear, but it is unclear whether
there is a threshol ose. At <8 weeks’ or >25 weeks’ gestation, a higher risk of intellectual disability in humans has not
been ocumente, even with oses exceeing 0.5 Gy or 50 ra
(International Commission on Radiological Protection, 2003).
Most estimates err on the conservative sie by assuming a linear
nonthreshold hypothesis. In a study of fetuses exposed to a low
raiation ose in the rst trimester, Guilbau an colleagues
TABLE 49-5. Some Measures of Ionizing Radiation
Exposure Number of ions produced by x-rays per kg
of air
Unit: roentgen (R)
Dose Amount of energy deposited per kg of
tissue
Modern unit: gray (Gy) (1 Gy = 100 rad)
(1000 mGy = 1 Gy)
Traditional unit: rad
Relative
effective
dose
Amount of energy deposited per kg
of tissue normalized for biological
effectiveness
(1000 mSv = 1 Sv)
Modern unit: sievert (Sv) (1 Sv = 100 rem)
Traditional unit: rem
TABLE 49-6. Deterministic Effects of Ionizing Radiation in Pregnancy
GA
(wks)
CA
(wks)
<50 mGy
(<5 rad) 50–100 mGy (5–10 rad) >100 mGy (>10 rad)
0–2 — None None None
3–4 1–2 None Probably none Low risk of spontaneous abortion
5–10 3–8 None Potential uncertain and probably too subtle
to be clinically detectable
Possible malformations increasing in
likelihood as dose increases
11–17 9–15 None Potential uncertain and probably too subtle
to be clinically detectable
Risk of decreased IQ or of mental retardation,
increasing in frequency and severity with
increasing dose
18–27 16–25 None None IQ deficits not detectable at diagnostic
doses
>27 >25 None None None applicable to diagnostic exposures
CA = conceptional age; GA = gestational age; IQ = intelligence quotient.872
Section 12
Medical and Surgical Complications
(2019) did not nd an increased risk for miscarriage, congenital
anomalies, or etal-growth restriction.
Reports have escribe high-ose raiation use to treat
women or malignancy, menorrhagia, an uterine myomas.
Dekaban (1968) described 22 infants with microcephaly, intellectual isability, or both ollowing exposure in the rst hal o
pregnancy to an estimate 2.5 Gy or 250 ra or therapeutic
raiation. Tese oses are also carcinogenic or the etus (Brent,
2015).
Summary of Fetal Radiation Exposure
From 8 to 15 weeks’ gestation, the fetus is most susceptible
to raiation-inuce intellectual isability (see able 49-6).
Whether this is a threshold or nonthreshold linear function
of dose is unresolved. e Committee on Biological Eects
(1990) estimates the risk of severe intellectual disability to be
as low as 4 percent or 0.1 Gy (10 ra) an as high as 60 percent or 1.5 Gy (150 ra). Recall that these oses are 2 to 100
times higher than those consiere maximal rom iagnostic
radiation. Importantly, cumulative doses from multiple procedures may reach the harmful range, especially at 8 to 15 weeks’
gestation. At 16 to 25 weeks’ gestation, the risk is less, and there
is no proven risk before 8 weeks or after 25 weeks (American
College of Obstetricians and Gynecologists, 2017).
Embryofetal risks from low-dose diagnostic radiation appear
to be minimal. Current evidence suggests that risks for mal-
ormations, growth restriction, or spontaneous abortion are
not increase rom a raiation ose o less than 0.05 Gy (5
ra). Brent (2009) conclue that gross congenital malormation rates woul not be greater with exposure to less than
0.2 Gy (20 ra). Diagnostic raiographs selom excee 0.1 Gy
(10 rad) and thus, these procedures are unlikely to cause deterministic eects (Strzelczyk, 2007). As emphasized by Groen
and coworkers (2012), 0.1 Gy is the radiation equivalent to
that rom more than 1000 chest x-rays.
■ Stochastic Effects
ese eects refer to random, presumably unpredictable oncogenic or mutagenic eects of radiation exposure. Stochastic
eects concern associations between fetal diagnostic radiation
exposure and increased risk of childhood cancers or genetic
diseases. Excess cancers can result from in utero exposure to
oses as low as 0.01 Sv or 1 ra (Doll, 1997; National Research
Council, 2006). e estimated risk of childhood cancer following fetal exposure to 0.03 Gy or 3 rad doubles the background
risk of 1 cancer in 600 exposed fetuses to that of 2 in 600
(Hurwitz, 2006).
In one report, in utero radiation exposure was linked to 10
soli cancers in aults rom age 17 to 45 years. Tere was a
ose-response relationship as previously note at the 0.1 Sv
or 10 rem threshold. ese cancers likely are associated with
a complex series o interactions between DNA an ionizing
radiation. ese interactions make it more problematic to predict cancer risk from low-dose radiation of less than 10 rem.
Importantly, below doses of 0.1 to 0.2 Sv, evidence of a carcinogenic eect is not convincing (Brent, 2009, 2014; Preston,
2008; Strzelczyk, 2007).
■ XRay Dosimetry
Estimates of dose to the uterus and embryo for various frequently use raiographic examinations are summarize in
Table 49-7. Imaging of maternal body parts farthest from
the uterus results in a very small ose o raiation scatter to
the embryo or etus. Te size o the woman, raiographic
technique, an equipment perormance are other variables
(Wagner, 1997). us, data in the table serve only as guidelines.
When the radiation dose for a specic individual is required,
a medical physicist should be consulted. e Health Physics
Society lists answers to questions commonly asked by patients
(Health Physics Society, 2020).
TABLE 49-7. Dose to the Uterus for Common Radiologic Procedures
Study View
Dosea per View
(mGy) No. Filmsb Dose (mGy)
Skullc AP, PA, Lat <0.0001 4.1 <0.0005
Chest AP, PAc, Latd <0.0001–0.0008 1.5 0.0002–0.0007
Mammogramd CC, Lat <0.0003–0.0005 4.0 0.0007–0.002
Lumbosacral spinee AP, Lat 1.14–2.2 3.4 1.76–3.6
Abdomene AP 1.0 0.8–1.63
Intravenous pyelograme 3 views 5.5 6.9–14
Hipb (single) AP 0.7–1.4
2.0 1–2
Lat 0.18–0.51
aCalculated for x-ray beams with half-value layers ranging from 2 to 4 mm aluminum
equivalent.
bBased on data and methods reported by Laws, 1978.
cEntrance exposure data from Conway, 1989.
dEstimates based on compilation of above data.
eBased on NEXT data reported in National Council on Radiation Protection and
Measurements, 1989.
AP = anterior-posterior; CC = cranial-caudal; Lat = lateral; PA = posterior-anterior.General Considerations and Maternal Evaluation 873
CHAPTER 49
■ Therapeutic Radiation
e Radiation erapy Committee Task Group of the American
Association o Physics in Meicine emphasizes careul iniviualization o cancer raiotherapy or the pregnant woman (Stovall,
1995). In some cases, shielding of the fetus and other safeguards
can be employed (Fenig, 2001; Nuyttens, 2002). However, in
other instances, the etus will be expose to angerous raiation
oses, an a careully esigne plan must be improvise (Prao,
2000). Moels that estimate the etal ose given uring maternal brain raiotherapy or tangential breast irraiation have been
developed (Mazonakis, 2017). e adverse pregnancy outcomes
that occur years ater abominopelvic raiotherapy are etaile
in Chapter 66 (p. 1164). (Brent, 2015; Wo, 2009).
■ Diagnostic Radiation
Radiographs
To estimate fetal risk, approximate x-ray dosimetry must be
known. According to the American College of Radiology, no
single iagnostic proceure results in a raiation ose signi-
cant enough to threaten embryo-fetal well-being (Hall, 1991).
For stanar raiographs, osimetry is presente in
Table 49-7. In pregnancy, the anterior-posterior-view chest
raiograph is the most common stuy, an etal exposure
is exceptionally small—0.0007 Gy or 70 mra. Te ose
with one abominal raiograph is higher—0.001 Gy or 100
mra—because the embryo or etus lies irectly in the x-ray
beam path. Te stanar intravenous pyelogram may excee
0.005 Gy or 500 mra because o several exposures. Te oneshot pyelogram described in Chapter 56 (p. 999) is useful
when urolithiasis or other causes o urinary tract obstruction
are unproven by sonography. Mammography an most
“trauma series” radiographs of an extremity, skull, or rib
deliver low doses because of distance from the fetus (CepedaMartins, 2021; Shakerian, 2015).
Fluoroscopy and Angiography
Dosimetry calculations are much more ifcult with these
proceures because o variations in the number o raiographs
obtaine, total uoroscopy time, an uoroscopy time uring which the etus lies in the raiation el. As shown in
Table 49-8, the range varies. Although the FDA limits the
exposure rate or conventional uoroscopy such as barium
stuies, special-purpose systems such as angiography units have
the potential or much higher exposure.
Angiography an vascular embolization may occasionally
be necessary or trauma an or serious maternal isorers. As
beore, a greater istance rom the embryo or etus lowers the
exposure and risk.
Computed Tomography
In a recent report describing nearly 3.5 million pregnancies,
the use of CT imaging from 1996 to 2016 increased vefold
(Kwan, 2019). Tese stuies are usually perorme by obtaining a spiral o 360-egree images that are postprocesse in
multiple planes. O these, the axial image remains the most
frequently obtained. Multidetector CT (MDCT) images are
now stanar or common clinical inications. Te most recent
etectors have more channels, an these multietector protocols may result in higher dosimetry compared with prior CT
imaging techniques. Several imaging parameters have an eect
on exposure (Brenner, 2007). ese include pitch, kilovoltage,
tube current, collimation, slice number, tube rotation, an
total acquisition time. If a study is performed with and without contrast, the ose is ouble because twice as many images
are obtaine. Fetal exposure also varies with maternal size an
etal size an position. As with plain raiography, the closer the
target area is to the etus, the greater the elivere ose.
Cranial CT imaging for evaluation of neurological disorders
and eclampsia is the most frequently performed CT study in
gravidas (Chaps. 41, p. 718 and 63, p. 1126). Nonenhanced
CT scanning is often used to detect acute hemorrhage within
the epiural, subural, or subarachnoi spaces (Fig. 49-3).
Raiation osage is negligible because o istance rom the
etus (Golberg-Stein, 2012).
Abdominal procedures are more problematic. Hurwitz
an associates (2006) employe a 16-channel multietector
scanner to calculate fetal exposure at 0 and 3 months’ gestation using a phantom model. Calculations were made for
three commonly requeste proceures in pregnant women
(Table 49-9). Te stuy showe their pulmonary embolism
protocol has the same osimetry exposure as the ventilationperusion (V/Q) lung scan iscusse subsequently. Although
the appenicitis protocol has the highest raiation exposure,
it is very useul clinically when MR imaging is not available. Using a greater pitch markedly decreases the dosimetry an yiels a sensitivity o 92 percent, a specicity o 99
percent, an a negative-preictive value o 99 percent (Lazarus, 2007). is is discussed further in Chapter 55 (p. 987).
TABLE 49-8. Estimated X-Ray Doses to the Uterus/
Embryo from Common Fluoroscopic
Procedures
Procedure
Dose to
Uterus
(mGy)
Fluoroscopic
Exposure in
Seconds (SD)
Cerebral angiographya <0.1 —
Cardiac angiographyb,c 0.65 223 (± 118)
Single-vessel PTCAb,c 0.60 1023 (± 952)
Double-vessel PTCAb,c 0.90 1186 (± 593)
Upper gastrointestinal seriesd 0.56 136
Barium swallowb,e 0.06 192
Barium enemab,f,g 20–40 289–311
aWagner, 1997.
bCalculations based on data of Gorson, 1984.
cFinci, 1987.
dSuleiman, 1991.
eBased on female data from Rowley, 1987.
fAssumes embryo in radiation field for entire examination.
gBednarek, 1983.
PTCA = percutaneous transluminal coronary angioplasty;
SD = standard deviation.874
Section 12
Medical and Surgical Complications
For suspecte urolithiasis, the multietector-scan protocol
is used if sonography is nondiagnostic. White and coworkers (2007) ientie urolithiasis in 13 o 20 women with
gestations aged an average of 26 weeks. Last, as shown in
Figure 49-4, abominal tomography is perorme i inicate
in the pregnant woman with severe trauma (Herfel, 2018;
Shakerian, 2015).
Most experience with chest CT imaging is with cases of
suspected pulmonary embolism. Historically, pulmonary scintigraphy—the V/Q scan—was recommene or pregnant
women by 70 percent of radiologists and chest CT angiography by 30 percent (Stein, 2007). However, most currently
agree that multidetector-CT pulmonary angiography (CTPA)
has improve accuracy because o increasingly aster acquisition times (Brown, 2014). Despite avances in technology,
scintigraphy is still recommene by the American Toracic
Society or gravias with a normal chest x-ray (Leung, 2012).
A higher use rate for CTPA has been reported, and dosimetry similar to that with V/Q scintigraphy has been emphasize (Brenner, 2007; Greer, 2015; romeur, 2019). Te
rapid turnaround time with current CTPA protocols at most
hospitals has avance its selection as the preerre moality
(Sheen, 2018). e algorithm in the YEARS study describes
the use o d-imer values an clinical criteria to ene a subgroup o gravias warranting urther imaging. Tus, the number of indicated CTPA studies resulting from this algorithm is
markedly reduced (van der Pol, 2019). In pregnancy, although
a negative d-imer test is helpul, these levels may be normally
elevate with increasing gestation an certain maternal complications (Chap. 55, p. 982).
O other aspects in stuy selection, the etal raiation
doses are lower with CT pulmonary angiography (CTPA)
compared with the V/Q scan. However, maternal chest
radiation doses are substantially higher with CTPA (van
Mens, 2017). e most recent ongoing Optimised Compute omography Pulmonary Angiography in Pregnancy
Quality and Safety (OPTICA) study is a prospective trial
TABLE 49-9. Estimated Radiation Dosimetry with
16-Channel Multidetector ComputedTomographic (MDCT) Imaging Protocols
Protocol
Dosimetry (mGy)
Preimplantation
3 Months’
Gestation
Pulmonary embolism 0.20–0.47 0.61–0.66
Renal stone 8–12 4–7
Appendix 15–17 20–40
A B
FIGURE 49-4 This woman in her third trimester was involved in a
high-speed motor vehicle accident. A. Maximum intensity projection
acquired for maternal indications readily identifies fetal skull fractures
(arrows). B. 3-D reformatted CT image in a bone algorithm demonstrates the fetal skeleton from data acquired during the maternal
examination. Again, the arrow marks one fracture site. (Reproduced
with permission from Bailey AA, Twickler DM: Perioperative imaging.
In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham
and Gilstrap’s Operative Obstetrics, 3rd ed. New York, NY: McGraw
Hill; 2017. Photo contributor: Dr. Travis Browning.)
FIGURE 49-3 An image from a noncontrast computed tomography head study demonstrates a large right-sided frontoparietal
temporal intraparenchymal hematoma (H). The midline (arrow) is
shifted to the left due to mass effect from the hematoma. (Reproduced with permission from Dr. Amanda Zofkie.)General Considerations and Maternal Evaluation 875
CHAPTER 49
using a uniform low-dose CTPA protocol to enable denitive recommendations. Until results are known, our reducedexposure CTPA protocol is recommended as the initial
preerre imaging moality in suspecte pulmonary embolism
(Chap. 55, p. 987).
CT pelvimetry is used by some before attempting breech
vaginal delivery (Chap. 28, p. 522). e fetal dose approaches
0.015 Gy or 1.5 ra, but use o a low-exposure technique may
reuce this to 0.0025 Gy or 0.25 ra.
Radiographic Contrast Agents
ese can be given intravenously or taken orally. Intravenous
contrast agents are consiere category B by the FDA. Tese
agents are ioinate an o low osmolality, an thus they cross
the placenta to the fetus. With water-soluble iodinated contrast, no cases o neonatal hypothyroiism or other averse
eects have been documented (American College of Obstetrics
an Gynecology, 2017). Oral contrast preparations, typically
containing ioine or barium, have minimal systemic absorption, and are unlikely to aect the fetus.
Nuclear Medicine Studies
Tese stuies are perorme by “tagging” a raioactive element
to a carrier that can be injecte, inhale, or swallowe. For
example, the raioisotope technetium-99m (c-99m) may be
tagge to re bloo cells, sulur colloi, or pertechnetate. Te
metho use to tag the agent etermines etal raiation exposure. Te amount o placental transer is obviously important,
but maternal renal clearance is also actore because o etal
proximity to her blaer. Measurement o raioactive technetium is based on its decay, and the units used are the curie (Ci)
or the Becquerel (Bq). Dosimetry is usually expresse in millicuries (mCi). e eective tissue dose is expressed in sievert
units (Sv) with conversion o 1 Sv = 100 rem = 100 ra (see
able 49-5).
Depening on the physical an biochemical properties
o a raioisotope, an average etal exposure can be calculate
(Wagner, 1997; Zanzonico, 2000). Commonly used radiopharmaceuticals an estimate absorbe etal oses are given in
Table 49-10. e radionuclide dose should be kept as low as
possible (Zanotti-Fregonara, 2017). Exposures vary with gestational age an are greatest earlier in pregnancy or most raiopharmaceuticals. One exception is the later eect of iodine-131
on the fetal thyroid (Wagner, 1997).
In a V/Q scan, perfusion is measured with injected Tc-99m
macroaggregate albumin, an ventilation is measure with
inhale xenon-127 or xenon-133. Fetal exposure with either is
negligible (Chan, 2002; Mountford, 1997).
Tyroi scanning with ioine-123 or ioine-131 selom
is indicated in pregnancy. However, with the trace diagnostic
doses used, fetal risk is minimal. In contrast, therapeutic doses
o raioioine to treat maternal Graves isease or thyroi cancer may cause etal thyroi ablation an cretinism.
Te sentinel lymphoscintigram is a commonly use preoperative stuy in nonpregnant women to etect the axillary lymph node most likely to have metastases from breast
cancer. c-99m–sulur colloi is use in this iagnostic stuy
(Newman, 2007; Spanheimer, 2009). Te calculate ose
approximates 0.014 mSv or 1.4 mra, which shoul not preclue its sae use uring pregnancy.
SONOGRAPHY
Te evelopment o sonography or stuy o the etus an
mother is one o the greater achievements in obstetrics. Te
technique has become virtually inispensable in everyay
practice. Its wide-ranging clinical uses are further discussed in
Chapters 14 and 15 and in other sections of this book.
MAGNETIC RESONANCE IMAGING
Magnetic resonance technology oes not use ionizing raiation,
an its use in pregnancy is constantly evolving (Gopirey,
2021; Mervak, 2019). Advantages include sharp resolution at
sot-tissue interaces, ability to characterize tissue composition,
an acquisition o images in any plane—particularly axial, sagittal, and coronal. A portion of Chapter 14 (p. 263) is devoted
to mechanisms that generate MR images, an imaging examples are provided throughout this book.
■ Safety
e update of the expert panel on MR safety of the ACR
was summarize by Kanal an colleagues (2013). Te panel
concluded that no harmful human eects are reported from
MR imaging. Similar conclusions were reached by the International Society or Ultrasoun in Obstetrics an Gynecology (2017).
When operated within standardized limits, maternal
an etal imaging can be saely perorme at clinical magnet strengths—3 tesla () an below. MR imaging can be
use regarless o trimester: (1) i the inormation cannot be
obtaine with another nonionizing moality, namely sonography; (2) i the stuy results will guie maternal or etal management uring pregnancy; an (3) i the imaging cannot be
elaye until the woman is no longer pregnant. Te ecision to
use a magnetic el strength >1.5 may be mae or specic
maternal indications. Early work also suggests imaging at 3 T is
safe and it improves fetal assessment (Chartier, 2019; Victoria,
2016). No emonstrable etal heart rate pattern changes occur
uring MR imaging o gravias (Vaeyar, 2000). Last, stuies
evaluating chilren expose in utero have shown no eleterious
eects (Kok, 2004; Reeves, 2010).
Contraindications to MR imaging include internal cardiac
pacemakers, neurostimulators, implanted debrillators and
inusion pumps, cochlear implants, shrapnel or other metal in
biologically sensitive areas, some intracranial aneurysm clips,
an any metallic oreign boy in the eye. O more than 51,000
nonpregnant patients scheule or MR imaging, one stuy
oun that only 0.4 percent ha an absolute contrainication
to the proceure (Dewey, 2007).876
Section 12
Medical and Surgical Complications
TABLE 49-10. Radiopharmaceuticals Used in Nuclear Medicine Studies
Study
Estimated Activity
Administered per
Examination (mCi)a
Weeks’
Gestationb
Dose to
Uterus/
Embryo (mSv)c
Brain 20 mCi 99mTc DTPA <12 8.8
12 7c
Hepatobiliary 5 mCi 99mTc sulfur colloid 12 0.45
5 mCi 99mTc HIDA 1.5
Bone 20 mCi 99mTc phosphate <12 4.6
Pulmonary
Perfusion 3 mCi 99mTc-macroaggregated
albumin
Any 0.45–0.57
(combined)
Ventilation 10 mCi 133Xe gas
Renal 20 mCi 99mTc DTPA <12 8.8
Abscess or tumor 3 mCi 67Ga citrate <12 7.5
Cardiovascular 20 mCi 99mTc-labeled red
blood cells
<12 5
3 mCi 210Tl chloride <12 11
12 6.4
24 5.2
36 3
Thyroid 5 mCi 99mTcO4 <8 2.4
0.3 mCi 123I (whole body)d 1.5–6 0.10
0.1 mCi 131I
Whole body 2–6 0.15
Whole body 7–9 0.88
Whole body 12–13 1.6
Whole body 20 3
Thyroid-fetal 11 720
Thyroid-fetal 12–13 1300
Thyroid-fetal 20 5900
Sentinel
lymphoscintigram
5 mCi 99mTc sulfur colloid
(1–3 mCi)
5
amCi = millicuries. To convert to mrad, multiply by 100.
bExposures are generally greater prior to 12 weeks compared with increasing
gestational ages.
cSome measurements account for placental transfer.
dThe uptake and exposure of 131I increases with gestational age.
DPTA = diethylenetriaminepentaacetic acid; Ga = gallium; HIDA = hepatobiliary
iminodiacetic acid; I = iodine; mCi = millicurie; mSv = millisievert; Tc = technetium;
TcO4 = pertechnetate; Tl = thallium.
Data from Adelstein, 1999; Bailey, 2017; Schwartz, 2003; Stather, 2002; Wagner, 1997;
Zanzonico, 2000.
■ Contrast Agents
Several dierent elemental gadolinium chelates are use to create
paramagnetic contrast. Tese cross the placenta an are oun
in the etus an placenta an are concentrate in amnionic
uid (Oh, 2015). In doses approximately 10 times the normal
human ose, a gaolinium-base contrast agent cause slight
developmental delay in rabbit fetuses. Inadvertant fetal exposure
usually occurs in early pregnancy (Bir, 2019). Te American
College of Radiology cites a study of 26 women given a gadolinium erivative in the rst trimester without averse etal
eects (Kanal, 2013). Despite this, routine use of gadolinium is
not recommended unless potential benets outweigh fetal risks
(American College of Obstetricians and Gynecologists, 2017;
American College of Radiology, 2020; Briggs, 2017). is recommenation stems rom a possible issociation o the toxic
gaolinium ion rom its ligan within amnionic ui an thus
potential prolonge exposure o the etus.
■ Maternal Indications
In some cases, MR imaging may complement CT, and in others, MR imaging is preferable (Mervak, 2019). MR imagingGeneral Considerations and Maternal Evaluation 877
CHAPTER 49
is also a superb tool to evaluate
the maternal abomen an retroperitoneal space. One example is evaluation o right lower
quarant pain in pregnancy,
specically with suspecte
appenicitis (Aguilera, 2018;
Tsai, 2017). It can aid detection an localization o arenal, renal, an gastrointestinal
lesions as well as pelvic masses
in pregnancy (Boy, 2012; Raj,
2020; ica, 2013).
Maternal central nervous
system abnormalities, such as
brain tumors or spinal trauma,
are more clearly seen with MR
imaging. is makes it invaluable in the iagnosis o neurological emergencies (Edlow, 2013). Other modalities include
MR urography or renal urolithiasis an cariac MR or investigating normal physiology, complex eects, an cariomyopathies (Mullins, 2012; Nelson, 2015; Stewart, 2016). Te
application o cariovascular MR imaging in pregnant women
is expaning (Ducas, 2019).
MR imaging helps also evaluate many pregnancy-specic
disorders. It is chosen by many to determine the degree and
extent of invasion in placenta accreta spectrum (Chap. 43,
p. 762). As discussed in Chapter 40 (p. 701), MR imaging
has provie important insights into the pathophysiology o
preeclampsia (Nelander, 2018; Zeeman, 2014). As discussed
in Chapter 37 (p. 656), CT and MR imaging are useful for
puerperal inection evaluation, but MR imaging provies better
visualization o the blaer ap area ollowing cesarean elivery
(Brown, 1999; Twickler, 1997). Last, preliminary studies of
placental function with MR imaging are promising (Hutter,
2019).
■ Fetal Indications
Fetal MR imaging provies a complement to sonography
(Laier-Narin, 2007; Sanrasegaran, 2006). Accoring to
Zaretsky and associates (2003a), MR imaging can be used to
isplay almost all elements o the stanar etal anatomical
survey. Moreover, the quality o three-imensional anatomical reconstruction with MR fetal imaging is superb (Werner,
2019). Te most requent etal inications are evaluation o
complex abnormalities o the brain, chest, an genitourinary systems (Williams, 2017). Reichel (2003) and Twickler
(2002) an their colleagues have valiate its use or etal
central nervous system anomalies an biometry (Fig. 49-5).
Others have escribe MR imaging o etuses with suprarenal
masses or with renal anomalies and oligohydramnios (Castro,
2019; Hawkins, 2008). Fetal weight estimation may be more
accurate with MR imaging than with sonography (Kaji,
2019; Zaretsky, 2003b). And MR imaging has been shown
to accurately ientiy etal anemia requiring transusions
(Jørgensen, 2019).
Fetal movement is problematic or MR imaging, but aster
acquisitions eliminate the problem. Morphology is primarily
assesse with ast 2-weighte sequences such as hal-Fourier
acquisition single shot turbo spin echo (HASTE) or single shot
ast spin echo (SSFSE). Fetal indications and ndings of MR
imaging are discussed more extensively in Chapter 14 (p. 266)
and throughout this book.
IMAGING DURING PREGNANCY
e American College of Obstetricians and Gynecologists
(2017) has reviewed the eects of radiographic, sonographic,
and magnetic-resonance exposure during pregnancy. Its suggeste guielines are shown in Table 49-11.
A B
FIGURE 49-5 Nullipara with a 27 weeks’ gestation. A. Axial T2-weighted MR image shows mild
fetal unilateral ventriculomegaly involving the left lateral ventricle (arrow). B. Sagittal T2-weighted
MR image demonstrates normal development of the corpus callosum (arrowheads) and vermis
(arrow).
TABLE 49-11. Guidelines for Diagnostic Imaging During Pregnancy and Lactation
Sonography and magnetic resonance (MR) imaging are not associated with fetal risk and are preferred options for imaging
in pregnancy
In general, radiation exposure during radiography, computed tomography (CT), or nuclear medicine imaging delivers a
dose much lower than that associated with fetal harm. If needed to supplement sonography or MR imaging or if more
readily available, these should not be withheld
With MR imaging, gadolinium contrast use should be restricted unless it significantly improves diagnostic accuracy to
benefit fetal or maternal outcome
Breastfeeding should not be interrupted after gadolinium administration
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