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Chapter 20
for her first child due to premature labor and fetal bradycardia fol- lowed by two normal deliveries at term.
On physical examination, the patient was pale and in severe pain. Blood pressure was 98/65 mm Hg and pulse rate initially 73 bpm. The hemoglobin was 6.0 mmol/l and serum hCG level was 22.252 iu/l. Her abdomen was soft with diffuse tenderness and a peritoneal reaction in the left iliac fossa. No intrauterine preg- nancy could be seen on transvaginal ultrasound examination. Ad- jacent to the left ovary, a hyperechoic mass measuring 60 · 40 mm was seen. The right ovary appeared normal on ultrasound and mini- mal amount of free fluid was found in the posterior cul-de-sac. A transabdominal ultrasound examination was about to be performed when the patient’s condition suddenly deteriorated with confusion, hypotension, and loss of consciousness.
My Management
a. Stabilize the patient and then perform immediate laparoscopy to control the bleeding
b. Immediate laparotomy c. Consult general surgery
Diagnosis and Assessment
This case illustrates a potentially life-threatening condition that re- mains a diagnostic challenge. The clinical condition of this patient, levels of hCG, and an empty uterus on ultrasound was highly sug- gestive of an advanced, ruptured ectopic pregnancy. Even though a left-sided adnexal mass had been visualized on ultrasound, the location of the pregnancy and the fetus was unknown.
Due to the history of previous term deliveries, a uterine anomaly was not suspected. The adnexal mass could potentially represent a ruptured uterine horn but was not suspected on the first ultra- sound examination. The recent pelvic examination performed by
147 20 Rudimentary Uterine Horn Pregnancy
the general practitioner, indicating a normal pregnancy, was also a confounding factor.
Despite the fact that an ectopic pregnancy was clinically high on the agenda, other diagnoses also had to be considered. Sometimes, an intrauterine pregnancy can be difficult to diagnose by trans- vaginal ultrasound examination and in this case a transabdominal ultrasound examination, which is often a valid supplementary in- vestigation, was not performed due to the emergency situation. The differential diagnoses at this time were adnexal torsion or rupture of a corpus luteum cyst. However, a ruptured tubal, cornual, or ab- dominal pregnancy was found to be a likely diagnosis.
Congenital uterine malformations occur in 1:200 to 1:600 wom- en [5]. The presence of a unicornuate uterus with a rudimentary horn is a result of an abnormal development of one of the Müllerian ducts. Uterine anomaly is often associated with renal anomalies due to the close embryologic relationship between the Müllerian and Wollfian ducts [9]. A rudimentary uterine horn may be com- municating or noncommunicating with the uterine cavity, and may or may not have a functional endometrial cavity (Fig. 20.1) [1]. It
Fig. 20.1 Variations of the unicorneate uterus: a communicating, b noncom- municating rudimentary horn, c rudimentary horn without a cavity, and d iso- lated unicorneate uterus [1]
is believed that 80–90 % of rudimentary uterine horn pregnancies arise in a noncommunicating horn due to transperitoneal migration of either fertilized ovum or spermatozoa [7] (Fig. 20.2). Rudimen- tary horn pregnancies are often diagnosed at a later stage in preg- nancy than what is typically observed in ectopic gestations and most cases present with acute uterine rupture.
In a review of 568 cases of rudimentary uterine horn pregnan- cies from 1900 to 1999, a rupture rate of 50 % was found with 80 % occurring before the third trimester [7]. The maternal mortality rate has fallen dramatically over time, from 23 % in the 1920s to cur- rently less than 0.5 % as a result of improved diagnosis and early treatment. Only a few reports exist of rudimentary horn pregnan- cies proceeding to term [8].
Women with uterine malformation have an increased risk of miscarriages and obstetric complications including intrauterine growth retardation, abnormal presentations, and preterm labor [9]. It is possible that uterine anomaly contributes to the preterm labor in our patient’s first pregnancy. Operative record of the ce- sarean delivery stated “a fibroma-like structure at the departure of the left salpinx.” Uterine anomalies can be classified according to the guidelines developed by the American Society of Reproductive Medicine [10], or according to a recent classification system for female genital anomalies developed by the European Society of
Fig. 20.2 Pregnancy in a noncommunicating rudimentary uterine horn arising due to transperitoneal migration of sperm
149 20 Rudimentary Uterine Horn Pregnancy
Human Reproduction and Endocrinology (ESHRE) and European Society for Gynecological Endoscopy (ESGE) [4].
Management
When a pregnant women presents with abdominal pain and symp- toms of hemorrhagic shock, immediate surgical intervention should be performed. The choice of operative method depends on the condition of the patient and surgeon’s expertise and experience.
Laparoscopy may be an alternative to laparotomy in the case of a hemodynamically stable patient. Surgery should include excision of the entire rudimentary horn. In addition to the morbidity associ- ated with uterine rupture, a rudimentary horn pregnancy carries an increased risk of abnormal implantation of the placenta, such as placenta accreta or percreta. Thus, the clinician should be prepared for the potential massive intraabdominal hemorrhage.
Early detection of rudimentary uterine horn pregnancies re- mains a clinical challenge. Even though more women undergo a first trimester ultrasound examination, the sensitivity of ultrasound in diagnosing rudimentary horn pregnancies is only 29 % [2].
Moreover, the diagnosis may be masked by a history of previous normal pregnancies, as in this case. On pelvic examination, the pa- tient may have an adnexal mass, causing deviation of the uterus to one side. Ultrasound findings may be suggestive of the presence of a bicornuate uterus.
The rudimentary horn pregnancy may be detected by the lack of continuity between the cervical canal and the lumen of the uterine horn. In some cases, a well-defined placenta fitting into the con- fines of the rudimentary horn may differentiate a rudimentary horn pregnancy from an abdominal pregnancy [6]. The diagnosis may be confirmed by magnetic resonance imaging. Once the diagno- sis of rudimentary horn pregnancy is established, surgery should be performed including removal of the ipsilateral Fallopian tube to prevent future ectopic pregnancies [2]. In rare cases, expectant management may be attempted [7], but this requires close monitor- ing of fetal growth and myometrial thickness and access for imme-
diate operative intervention. If a rudimentary uterine horn is identi- fied before conception, elective surgical removal by laparoscopy is recommended [3].
Outcome
An emergency laparotomy was performed revealing a massive hemoperitoneum. On the left side of the uterus, a ruptured rudi- mentary horn containing the placenta was found. The fetus was found floating in the abdominal cavity. According to its crown–
heel length, it was estimated to be 16 weeks of gestational age.
There were no visible malformations. An excision of the rudimen- tary uterine horn along with the placenta and a left salpingectomy were performed. Estimated blood loss was 4.8 l and blood transfu- sions and fresh-frozen plasma were given. The woman recovered without complications and was discharged 4 days later.