CHAPTER 6 First-Trimester Abortion PDF

ITESM Access Provided by: Williams Gynecology, 4e CHAPTER 6: First­Trimester Abortion TERMINOLOGY Abortion is the spontaneous or induced termination of pregnancy before fetal viability. Thus, miscarriage and abortion appropriately are terms used interchangeably in a medical context. But, because po...

ITESM Access Provided by: Williams Gynecology, 4e CHAPTER 6: First­Trimester Abortion TERMINOLOGY Abortion is the spontaneous or induced termination of pregnancy before fetal viability. Thus, miscarriage and abortion appropriately are terms used interchangeably in a medical context. But, because popular use of abortion by laypersons implies a deliberate intact pregnancy termination, many prefer miscarriage for spontaneous fetal loss. Both terms will be used throughout this chapter. For statistical and legal purposes, viability is usually defined by pregnancy duration and fetal birthweight. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) define abortion as any pregnancy termination—spontaneous or induced—before 20 weeks’ gestation or with a fetus born weighing 20 ng/mL support the diagnosis of a healthy pregnancy. However, progesterone levels often lie between these thresholds, are then considered ITESM indeterminate, and thus are less informative. Access Provided by: TVS can document the location and viability of a gestation. If this cannot be done, then a PUL is diagnosed. Notably, a consensus conference in 2012 concluded that prior sonographic criteria for fetal viability yielded unacceptably high rates of viable IUPs being falsely diagnosed as nonviable or as PULs (American College of Obstetricians and Gynecologists, 2018a; Doubilet, 2014). Such errors can lead to unnecessary surgical or medical treatment, interruption of a viable IUP, or incorrect assumption that a woman is at recurrent risk for an ectopic pregnancy. Because of this, as shown in Table 6­3, more stringent guidelines were proposed to diagnose pregnancy failure (Doubilet, 2014). TABLE 6­3 Society of Radiologists in Ultrasound Guidelines for Early Pregnancy Loss Diagnosis Diagnostic Sonographic Findings CRL ≥7 mm and no heartbeat MSD ≥25 mm and no embryo Absence of embryo with heartbeat ≥2 weeks after a scan showed a gestational sac without a yolk sac Absence of embryo with heartbeat ≥11 days after a scan showed a gestational sac with a yolk sac CRL = crown­rump length; MSD = mean sac diameter. One early TVS sign of an IUP is the gestational sac. This anechoic fluid collection represents the exocoelomic cavity. It may be encircled by two echogenic external layers, the double­decidual sign, which represent the decidua parietalis and decidua capsularis (Fig. 6­1). The gestational sac can usually be seen by 4.5 weeks with maternal β­hCG levels between 1500 and 2000 mIU/mL (Barnhart, 1994). More recently, Connolly and colleagues (2013) reported that a threshold value of 3500 mIU/mL may be required to detect a gestational sac in 99 percent of cases. This level is now recommended by the American College of Obstetricians and Gynecologists (2018f). Importantly, a gestational sac may appear similar to other intrauterine fluid accumulations such as the pseudogestational sac (pseudosac) present with ectopic pregnancy (Fig. 7­4, p. 165). A pseudosac may be excluded once a definite yolk sac or embryo is seen inside the sac. The diagnosis of an IUP should be made cautiously if the yolk sac is not yet seen (American College of Obstetricians and Gynecologists, 2018g). FIGURE 6­1 Early intrauterine pregnancy. A. Sonogram shows the anechoic gestational sac surrounded by two concentric echogenic layers, which are the inner decidua capsularis (arrow) and the peripheral decidua parietalis (arrow). B. The drawing shows the anatomy of an early pregnancy. C. The yolk sac (arrow) is circular and anechoic, and in this image, it lies to the right of its adjacent embryo. Downloaded 2024­3­5 5:51 A Your IP is 104.214.75.120 CHAPTER 6: First­Trimester Abortion, ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 6 / 42 ITESM Access Provided by: The yolk sac is a circular, 3­ to 5­mm­diameter anechoic structure. It is typically seen within the gestational sac at approximately 5.5 weeks’ gestation and with a mean sac diameter (MSD) ≥10 mm. At approximately 6 weeks’ gestation, a 1­ to 2­mm embryo adjacent to the yolk sac can be found (see Fig. 6­1). Absence of an embryo in a sac with a MSD of 16 to 24 mm is suspicious for pregnancy failure (Doubilet, 2014). Cardiac motion can be detected at 6 to 6.5 weeks’ gestation, at an embryonic length of 1 to 5 mm. Shown in Table 6­3, absent cardiac activity at certain stages can be used to diagnose pregnancy failure. Management With threatened abortion, bed rest is often recommended but does not improve outcomes. Neither has treatment with a host of medications and hormones that include progesterone and chorionic gonadotropin (Devaseelan, 2010). Acetaminophen­based analgesia will help relieve cramping discomfort. If anemia or hypovolemia is significant from active bleeding, pregnancy evacuation is generally indicated. In cases in which there is a live fetus, less often, some instead may choose transfusion and further observation. Inevitable Abortion Amnionic fluid leaking through a dilated cervix portends almost certain abortion. Sonography will usually show markedly diminished fluid volume. Following such membrane rupture, either uterine contractions begin promptly or infection develops. Rarely is a gush of vaginal fluid during the first Downloaded 2024­3­5 5:51 A Your IP is 104.214.75.120 half of pregnancy without serious consequence. Page 7 / 42 CHAPTER 6: First­Trimester Abortion, ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility In the rare case, fluid may have collected previously between the amnion and chorion and may not be associated with pain, fever, or bleeding. TVS will typically show normal fluid volume. If a live fetus and normal fluid volume is documented, diminished activity with observation is reasonable. After 48 fetus, less often, some instead may choose transfusion and further observation. ITESM Access Provided by: Inevitable Abortion Amnionic fluid leaking through a dilated cervix portends almost certain abortion. Sonography will usually show markedly diminished fluid volume. Following such membrane rupture, either uterine contractions begin promptly or infection develops. Rarely is a gush of vaginal fluid during the first half of pregnancy without serious consequence. In the rare case, fluid may have collected previously between the amnion and chorion and may not be associated with pain, fever, or bleeding. TVS will typically show normal fluid volume. If a live fetus and normal fluid volume is documented, diminished activity with observation is reasonable. After 48 hours, if no additional amnionic fluid has escaped and no bleeding, cramping, or fever is noted, a woman may resume ambulation. Initial abstinence from intercourse and exercise also is recommended. Instead, with bleeding, cramping, or fever, abortion is considered inevitable, and the uterus is evacuated. Incomplete Abortion With first­trimester losses, death of the embryo or fetus nearly always precedes spontaneous expulsion. Death of the conceptus is usually accompanied by hemorrhage into the decidua basalis. This is followed by adjacent tissue necrosis that stimulates uterine contractions and expulsion. An intact gestational sac is generally filled with fluid and may or may not contain an embryo or fetus. With miscarriage, bleeding usually begins first, and abdominal cramping follows hours to days later. Low­midline rhythmic cramps; persistent low backache with pelvic pressure; or dull and midline suprapubic discomfort are common symptoms. Partial or complete placental separation and dilation of the cervical os is termed incomplete abortion. The fetus and the placenta may remain entirely within the uterus or partially extrude through the dilated os. Before 10 weeks, they are frequently expelled together, but later in pregnancy, they deliver separately. Management options of incomplete abortion include curettage, medical abortion, or expectant management in clinically stable women (Table 6­4) (Kim, 2017). With surgical therapy, additional cervical dilation may be necessary before suction curettage is performed (p. 152). In others, retained placental tissue simply lies loosely within the cervical canal and allows easy extraction with ring forceps. The removed products of conception are sent to pathology for standard histologic analysis. By this, products of conception are confirmed, and gestational trophoblastic disease is excluded. TABLE 6­4 Randomized Controlled Studies for Management of Early Pregnancy Loss Study Inclusion Criteria No. Treatment Arms Outcomes Nguyen (2005) Incomplete SAB 149 (1) PGE1, 600 μg orally 60% completed at 3 d (2) PGE1, 600 μg orally initially and at 4 hour 95% at 7 d; 3% curettage (1) PGE1, 800 μg vaginally 71% completed at 3 d; (2) Vacuum aspiration 16% failure Zhang (2005) Pregnancy failurea 652 97% successful Trinder (2006) (MIST Trial) Incomplete SAB; missed AB 1200 (1) Expectant 50% curettage (2) PGE1, 800 μg vaginally 38% curettage ± 200 mg mifepristone 5% repeat curettage (3) Suction curettage Dao (2007) Torre (2012) Incomplete SAB First­trimester miscarriageb 447 174 (1) PGE1, 600 μg orally 95% completed (2) Vacuum aspiration 100% completed (1) Immediate—PGE1, 200 μg orally 81% completed Day 2—400 μg vaginally 19% curettage (2) Delayed—no treatment; 57% completed TVS days 7 and 14 43% curettage Downloaded 2024­3­5 5:51 A Your IP is 104.214.75.120 aIncludes anembryonic gestation, embryonic or fetal death, without signs of incomplete SAB. CHAPTER 6: First­Trimester Abortion, ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility b Includes anembryonic gestation, embryonic or fetal death, or incomplete or inevitable SAB. Page 8 / 42 (Table 6­4) (Kim, 2017). With surgical therapy, additional cervical dilation may be necessary before suction curettage is performed (p. 152). In others, ITESM retained placental tissue simply lies loosely within the cervical canal and allows easy extraction with ring forceps. The removed products of conception Access Provided by: are sent to pathology for standard histologic analysis. By this, products of conception are confirmed, and gestational trophoblastic disease is excluded. TABLE 6­4 Randomized Controlled Studies for Management of Early Pregnancy Loss Study Inclusion Criteria No. Treatment Arms Outcomes Nguyen (2005) Incomplete SAB 149 (1) PGE1, 600 μg orally 60% completed at 3 d (2) PGE1, 600 μg orally initially and at 4 hour 95% at 7 d; 3% curettage (1) PGE1, 800 μg vaginally 71% completed at 3 d; (2) Vacuum aspiration 16% failure Zhang (2005) Pregnancy failurea 652 97% successful Trinder (2006) (MIST Trial) Incomplete SAB; missed AB 1200 (1) Expectant 50% curettage (2) PGE1, 800 μg vaginally 38% curettage ± 200 mg mifepristone 5% repeat curettage (3) Suction curettage Dao (2007) Torre (2012) Incomplete SAB First­trimester miscarriageb 447 174 (1) PGE1, 600 μg orally 95% completed (2) Vacuum aspiration 100% completed (1) Immediate—PGE1, 200 μg orally 81% completed Day 2—400 μg vaginally 19% curettage (2) Delayed—no treatment; 57% completed TVS days 7 and 14 43% curettage aIncludes anembryonic gestation, embryonic or fetal death, without signs of incomplete SAB. b Includes anembryonic gestation, embryonic or fetal death, or incomplete or inevitable SAB. SAB = spontaneous abortion; PGE1= prostaglandin E1; TVS = transvaginal sonography. Complete Abortion In some cases, expulsion of the entire pregnancy is completed before a patient presents for care. In such cases, a history of heavy bleeding, cramping, and tissue passage at home is common. On pelvic examination, the cervical os is closed. Patients are encouraged to bring in passed tissue, which may be a complete gestation, blood clots, or a decidual cast. The last is a layer of endometrium in the shape of the uterine cavity that when sloughed can appear as a collapsed sac (Fig. 7­7, p. 167). If a gestational sac is not identified grossly in the expelled specimen, sonography is performed to differentiate a complete abortion from threatened abortion or ectopic pregnancy. With TVS, characteristic intrauterine findings of a complete abortion include a thickened endometrium without a gestational sac. However, this does not guarantee a recent IUP. Condous and associates (2005) described 152 women with heavy bleeding, an empty uterus with endometrial thickness