Michelle Meglin
History of present illness
A 28-year-old gravida 3, para 1-0-1-1 woman presents to your clinic with a positive pregnancy test and vaginal spotting. Her gestational age is 10 weeks 2 days by sure last menstrual period. This is herfirst visit during this pregnancy. She reports intermittent vaginal spotting for the last two weeks but became alarmed today when it got heavier. She denies abdominal pain, nausea, vomiting, or urinary symptoms.
Her obstetrical history is significant for a term vaginal delivery and an earlyfirst-trimester spontaneous abortion. She has no medical or surgical history but reports an episode of pelvic inflammatory disease as a teenager. She smokes one pack of cigarettes daily. She lives two hours away from the hospital and does not have reliable transportation for clinic visits.
Physical exam
General appearance:Woman who is in no apparent distress Vital signs:
Temperature: 37.0°C Pulse: 85 beats/min
Blood pressure: 115/80 mmHg Respiratory rate: 16 breaths/min Oxygen saturation: 100% on room air BMI: 27 kg/m2
Chest:Clear to auscultation Cardiovascular:Unremarkable
Abdomen:Soft, nontender, nondistended, no masses External genitalia:Unremarkable
Vagina:One scopette of brownish blood, otherwise unremarkable
Cervix:External os closed, no active bleeding
Uterus:Anteverted, moderate tenderness to palpation, six to eight weeks’size, mobile
Adnexa:No masses, mild tenderness to palpation in the left adnexa, no tenderness on the right
Laboratory studies:
Beta-hCG: 18 000 mIU/mL CBC: Normal
Liver function tests: Normal Creatinine: Normal
Blood type: O positive
Imaging:Transvaginal ultrasound shows an empty uterine cavity with a large 4 cm gestational sac at the left cornua
surrounded by thin (<5 mm) myometrium, fetal cardiac motion noted. Normal appearing bilateral ovaries. Nofluid in the posterior cul-de-sac (Fig. 31.1)
How would you manage this patient?
This patient has an interstitial ectopic pregnancy. Given her several relative contraindications to medical therapy including a gestational sac greater than 3.5 cm, cardiac motion, and concerns regarding compliance with follow-up due to her travel distance and lack of transportation, surgical manage- ment is most appropriate. She underwent a laparoscopic cornuostomy after injection of vasopressin (into the myome- trium surrounding the pregnancy) without complication. She had an uneventful postoperative course and was discharged on postoperative day 1. Pathology confirmed products of conception. Beta-human chorionic gonadotropin (beta-hCG) levels were followed to zero.
Interstitial pregnancy
Interstitial pregnancy is a type of ectopic pregnancy in which implantation occurs in the interstitial portion of the fallopian tube, defined as the proximal portion of tube contained within the myometrium. This proximal portion of the fallopian tube lies within the muscular uterine wall and has greater distensi- bility compared to distal portions of the tube. Interstitial pregnancy is often confused with cornual pregnancy, which refers to a pregnancy within a uterine horn in a patient with a Mullerian anomaly [1]. Interstitial pregnancies account for approximately 2.5% of ectopic pregnancies [1].
Risk factors for interstitial pregnancy are similar to those for distal tubal pregnancies and include a history of prior ectopic pregnancy, sexually transmitted disease/pelvic inflam- matory disease, tubal surgery, failed sterilization, use of assisted reproductive therapy (particularly in-vitro fertiliza- tion), and smoking [2]. Patients with an interstitial pregnancy typically present with abdominal pain and vaginal bleeding in thefirst trimester; however, the incidence of vaginal bleeding is less common than that with a distal tubal ectopic pregnancy [3]. While it was once thought that interstitial pregnancies presented and ruptured at later gestational ages due to the greater distensibility of the myometrium covering the intersti- tial segment of the fallopian tube, recent evidence suggests the average gestational age at diagnosis and rupture is 6.9–8.0 weeks, similar to distal tubal ectopic pregnancies [3]. Rupture of an interstitial pregnancy is associated with risk of severe
Acute Care and Emergency Gynecology, ed. David Chelmow, Christine R. Isaacs and Ashley Carroll. Published by Cambridge University Press.
© Cambridge University Press 2015.
hemorrhage due to the potential larger size of the pregnancy and proximity to the uterine and ovarian arteries. In cases of severe hemorrhage, the mortality rate is as high as 2.5%
making early diagnosis and management critical [3].
Early diagnosis of interstitial pregnancy has improved with the advent of high resolution transvaginal ultrasound and sensitive quantitative beta-hCG assays. Several ultrasono- graphic characteristics have been identified that help in diag- nosing an interstitial pregnancy: an empty uterine cavity, an eccentric gestational sac, a chorionic sac at least 1 cm from the lateral edge of the uterine cavity, a thin (<5 mm) myometrial layer surrounding the gestational sac, and the“interstitial line”
sign. The interstitial line sign describes an echogenic line extending from the lateral aspect of endometrial cavity that abuts the gestational sac. Occasionally, the diagnosis remains
unclear by transvaginal ultrasound and is rather made intrao- peratively withfindings of a bulging pregnancy in the cornua, lateral to the fundus and round ligament (Fig. 31.2) [3].
Earlier diagnosis of interstitial pregnancy has led to alter- natives to traditional management, which typically involved hysterectomy or cornual wedge resection via laparotomy.
Nonsurgical treatment options include systemic methotrexate, local injection of cytotoxic agents, and, rarely, expectant management. Systemic methotrexate should be administered using one of the three treatment protocols used for distal tubal ectopic pregnancies: single-dose regimen, two-dose regimen, or a fixed multidose regimen [2]. To consider methotrexate management, patients must be hemodynamically stable without suspicion for a ruptured ectopic pregnancy, able to comply with follow-up surveillance, and without medical
Fig. 31.2 Left-sided interstitial pregnancy on laparoscopy.
Fig. 31.1 Transvaginal ultrasound showing the uterine fundus in a transverse plan. The gestational sac is eccentric, separate from the endometrial stripe and surrounded by a thin layer of myometrium.
contraindications to consider methotrexate. Absolute contra- indications to methotrexate therapy are breast-feeding, immunodeficiency, liver disease, blood dyscrasias, active pul- monary disease, peptic ulcer disease, known sensitivity to methotrexate, or other evidence of hepatic, renal or hemato- logic dysfunction. To evaluate for possible contraindications a complete blood count, creatinine and liver transaminases should be obtained. Relative contraindications where one should consider surgical management over methotrexate therapy are a gestation sac greater than 3.5 cm and fetal cardiac motion [2]. Case series have reported up to 80–94% success rates for treatment of interstitial pregnancy when using systemic methotrexate [3]. Low initial beta-hCG levels (<5000–9000 mIU/mL) is the strongest predictor of successful methotrexate management [1]. In the appropriately selected patient, systemic methotrexate is an appropriate first-line therapy [3].
Local injection of cytotoxic agents (most commonly meth- otrexate) under laparoscopic, ultrasound, or hysteroscopic guidance has been reported as an alternative treatment. From the limited data, local injection appears safe and effective compared with systemic methotrexate, but it is unclear if this method provides significant additional benefit to justify the procedure and cost. Expectant management of interstitial pregnancy should be reserved for the stable patient with spon- taneously declining beta-hCG levels. These patients must be monitored closely for signs of rupture, and often requiring inpatient hospital monitoring [3].
Traditionally, surgical treatment of interstitial pregnancy involved a laparotomy to perform a cornual wedge resection, or hysterectomy since cases were often diagnosed after uterine rupture which lead to hemorrhage and significant uterine trauma. Surgical treatment remains the recommended therapy in cases of ruptured interstitial pregnancy and is also appro- priate if there are contradictions to medical therapy (as in the case of our patient) including if patients are not agreeable to medical management or unable to comply with follow-up, if medical management fails (as evident by rising beta-HCG levels), or in patients who would not accept life-saving blood products (should subsequent rupture result in severe hemor- rhage). Surgical excision can be performed via laparotomy or laparoscopy using one of several techniques such as cornuostomy, salpingostomy, and cornual resection. Cor- nuostomy involves removal of the pregnancy without removal of the surrounding myometrium via a linear incision in the myometrium overlying the pregnancy and extraction of the gestational tissue. Salpingostomy may similarly be performed
at the site where the tube enters the fundus. Cornuostomy and salpingostomy are more suitable in cases of early, small (<4 cm) interstitial pregnancies. Cornual resection involves removes the interstitial pregnancy and surrounding myome- trium and can be performed via laparoscopy in settings with appropriate resources and surgeon experience. Several methods to minimize blood loss have been described, the most common of which is injection of vasopressin into the myome- trium surrounding the pregnancy. Transcervical evacuation of the pregnancy using a suction curettage under laparoscopic and ultrasound guidance has also been described in case series as an alternative surgical therapy [3].
Surveillance after medical treatment of interstitial preg- nancy involves outpatient monitoring for signs/symptoms of rupture and observing beta-hCG levels to resolution as per methotrexate protocol guidelines [2]. Patients treated surgically with cornuostomy or salpingostomy remain at risk for persistent interstitial pregnancy due to suboptimal removal of all pregnancy tissue and should also have beta-hCG surveillance. In subsequent pregnancies patients with a prior interstitial pregnancy are at risk for recurrence and an early first-trimester ultrasound should be performed to identify pregnancy location. Additionally, it is recommended that patients with prior surgical management of interstitial preg- nancy be delivered by Cesarean section at term due to reports of uterine rupture at the site of prior cornual excision [3].
Key teaching points
Interstitial pregnancy is an uncommon type of ectopic pregnancy, but needs to be recognized early due the increased risk of severe hemorrhage and death.
Diagnosis involves ultrasoundfindings of an empty uterine cavity, an eccentric gestational sac, a chorionic sac at least 1 cm from the lateral edge of the uterine cavity, a thin (<5 mm) myometrial layer surrounding the gestational sac, and the“interstitial line”sign.
In asymptomatic, hemodynamically stable patients without contraindications, systemic methotrexate is an appropriate first-line therapy for treatment of interstitial pregnancy.
Surgical management may be accomplished via laparoscopy or laparotomy with cornuostomy, salpingostomy, or cornual resection.
Patients who have undergone medical or conservative surgical treatment should be followed until beta-hCG is undetectable due to the risks of interstitial rupture and/or persistent interstitial pregnancy tissue.
References
1. Chetty M, Elson J. Treating non-tubal ectopic pregnancy.Best Prac Res Clin Obstet Gynaecol2009;23(4):529–38.
2. American College of Obstetricians and Gynecologists. Medical Management of Ectopic Pregnancy. Practice Bulletin No. 94.Obstet Gynecol2008;111(6):
1479–85.
3. Moawad NS, Mahajan ST, Moniz MH, Taylor SE, Hurd MW. Current diagnosis and treatment of interstitial pregnancy.Am J Obstet Gynecol 2010;202(1):15–29.
Case 31: Early pregnancy spotting and an unusual ultrasound