CASE REPORT culdocentesis; ectopic pregnancy

Serous Culdocentesis in Ectopic Pregnancy: A Report of Two Cases Caused by Coexistent Corpus Luteum Cysts Two cases of women with large-volume serous culdocentesis results are presented. Both patients ultimately had ectopic pregnancies diagnosed surgically, and aspiration into coexistent corpus luteum cysts caused the "false-negative" culdocentesis results. The accuracy of culdocentesis and its continued role in the workup of the patient with possible ectopic pregnancy is reviewed. Because the corpus luteum is a cystic structure present in all pregnancies during the first seven weeks, cyst aspiration is always a possibility and should be suspected when large amounts of serous fluid are obtained by culdocentesis. Such results should be considered nondiagnostic and do not exclude a coexistent ectopic pregnancy. [Elliot M, Riccio J, Abbott J: Serous culdocentesis in ectopic pregnancy: A report of two cases caused by coexistent corpus luteum cysts. Ann Emerg Med April 1990;19:407-410.] INTRODUCTION Making or excluding the diagnosis of ectopic pregnancy at the first visit to the emergency department is a considerable challenge to physicians. The clinical diagnosis of ectopic pregnancy, based on the triad of abdominal pain, amenorrhea, and vaginal bleeding, is insensitive, occurring in 50% to 80% of patients in reported series.i, ~ In addition, the clinical picture of ectopic pregnancy is nonspecific, and is often indistinguishable from threatened abortion and corpus luteum cyst rupture in early pregnancy. 3,4 When ultrasound is nondiagnostic and quantitative, human chorionic gonadotropin (hCG) determinations are either not helpful or not immediately available, culdocentesis has been used to improve the accuracy of ectopic pregnancy diagnosis. We present two cases of falsely "negative" (ie, serous) culdocentesis in ectopic pregnancy patients with coexistent corpus luteum cysts and review the usefulness and limitations of culdocentesis.

Mark Elliot, MD* John Riccio, MD* Jean Abbott, MD, FACEPt Denver, Colorado From the Department of Emergency Medicine, Denver General Hospital;* and the Section of Emergency Medicine and Trauma, Emergency Medicine Clinical Research Center, University of Colorado Health Sciences Center/ Denver. Received for publication July 10, 1989. Revision received October 10, 1989. Accepted for publication October 26, 1989. Address for reprints: Jean Abbott, MD, Section of Emergency Medicine and Trauma, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, Colorado 80262.

CASE REPORTS Case One A 35-year-old G2, P1 woman with six weeks of amenorrhea first presented to the walk-in clinic with a six-day history of right lower quadrant abdominal pain and intermittent vaginal spotting. She was found to have a positive serum hCG, a hematocrit of 42%, and a real-time pelvic ultrasound demonstrating no visible intrauterine pregnancy or adnexal masses. A culdocentesis was performed, yielding 10 mL of clear, straw-colored fluid. A quantitative ~-hCG level was drawn, and she was discharged home with instructions to return if she had further pain; she was also scheduled to return to the ED in 48 hours for a repeat quantitative hCG level. The patient failed to return in 48 hours for blood work and re-evaluation, but she did return on her own at 72 hours because of increased pain. On presentation, her vital signs were significant for a 20-point increase in her pulse on standing, without significant changes in her blood pressure. Physicial examination revealed mild right lower quadrant pain without rebound or guarding. Pelvic examination revealed a small amount of dark brown blood in the vaginal vault with a closed os and a six- to eight-week uterine size. The right adnexa was moderately tender with no palpable

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Annals of Emergency Medicine


SEROUS CULDOCENTESIS Elliot, Riccio & Abbott

masses. The patient's hematocrit was 40% and she had resolution of her orthostasis after 1 L IV normal saline. A formal ultrasound revealed a cystic mass in the cul-de-sac. Quantitative B-hCG from the first visit was reported as 9,215 mIU/mL. A repeat B-hCG on the second visit was 6,690 mIU/mL (IRP). Repeat culdocentesis yielded nonclotting blood, and the patient was taken for laparotomy. Surgery revealed a right 4 x 6 cm unruptured ampullary tubal gestation with hemoperitoneum and a right unruptured cyst extending into the cul-de-sac. A right salpingectomy and cystectomy were performed, and the patient was discharged on her second postoperative day w i t h o u t complications. Case T w o A 25-year-old G7, P3 woman, with a last menstrual period 20 days earlier, presented to the ED with bilateral lower quadrant abdominal pain and i n t e r m i t t e n t vaginal bleeding. She denied fever, chills, vomiting, diarrhea, or previous ectopic pregnancies. A serum hCG was positive, and her hematocrit was 42%. On physical examination her vital signs were stable, with no orthostatic changes, and her abdominal examination was nontender without masses, rebound, or guarding. Pelvic examination revealed a slightly enlarged, nontender uterus with minimal bilateral adnexal tenderness and no palpable masses. Her os was closed with no bleeding. A formal ultrasound demonstrated no visible intrauterine pregnancy and a 4 x 5 cm cystic mass in the left adnexa. Culdocentesis returned 10 mL of clear, straw-colored fluid. She was discharged home with ectopic precautions and instructed to return in 48 hours for a repeat quantitative hCG level. Her hCG on the initial visit was 1,724 mIU/mL. The patient was seen again at two and four days later for repeated quantitative hCG levels (2,410 mIU/mL and 2,345 mIU/mL, respectively), but had no further pain. The patient returned seven days after her initial visit complaining of increased right lower quadrant pain. Her examination revealed only mild right adnexal tenderness. A repeat culdocentesis again returned 10 mL of clear, strawcolored fluid. The patient was taken to the operating room for laparost04/408

copy, which revealed an unruptured right ampullary gestation and a left corpus l u t e u m cyst that extended i n t o t h e c u l - d e - s a c . Free i n t r a peritoneal blood was found at surgery. A right partial salpingectomy was performed w i t h o u t complications, and the patient had an unremarkable postoperative recovery.

DISCUSSION The clinical diagnosis of ectopic pregnancy is extremely difficult in some patients because pelvic pain, vaginal bleeding, and even adnexal masses m a y been seen in normal early pregnancy or in other disease states and may be absent in ectopic pregnancies. One of the most common problems is differentiating ectopic pregnancy from a ruptured corpus luteum cyst in pregnancy. Because ectopic pregnancy and corpus luteum cyst can coexist, considerable confusion may occur. The goal in the ED should be to choose such tests intelligently to diagnose or exclude ectopic pregnancy at the time of initial presentation for medical care whenever possible. Although culdocentesis is usually very accurate in identifying ectopic pregnancy (even when peritonitis is not present s ) and in differentiating ectopic pregnancy from corpus luteum cyst rupture, the two cases we report d e m o n s t r a t e that problems can exist in the interpretation of culdocentesis results. The corpus l u t e u m derives from the ovarian follicle during the postovulatory or secretory phase of the menstrual cycle. The corpus luteum secretes progesterone and other hormones to prepare the endometrium for implantation of a fertilized ovum. Degeneration occurs at the time of menstruation unless fertilization of an ovum has occurred. Production of hCG by the trophoblast, starting at the time of implantation, stimulates a persistent corpus luteum that continues to function in a secretory capacity during the first seven weeks of pregnancy. After that time, the placenta is sufficiently established as the primary organ of steroidogenesis, and involution of the corpus luteum OCCURS. 6

The corpus l u t e u m is n o r m a l l y cystic in pregnancy, often reaching 5 cm in diameter, and further enlargement is occasionally seen. Pain from cyst rupture is a common mimic of ectopic pregnancy. Confusion arises Annals of Emergency Medicine

because spillage of cyst fluid can present clinically in the same manner as leakage of blood from fimbriae of the fallopian tubes in an ectopic pregnancy. The typical patient presents with local or diffuse peritonitis in the first trimester of pregnancy and may have an adnexal mass (or at least tenderness). Both of the most comm o n ancillary studies, u l t r a s o u n d and quantitative hCG determination, have their limitations in differentiating ectopic pregnancy from an intrauterine pregnancy with a corpus luteum cyst. Ultrasound is useful when an intrauterine pregnancy can be identified. With transabdominal imaging, this is reliable when the gestation is more than 42 days (hCG level greater than 6,000 mIU/mL [IRP]), but this only occurs in 10% to 30% of ectopic pregnancy patients, z Even with transvaginal techniques, which can detect an intrauterine pregnancy about one week earlier and more frequently identify the actual ectopic gestation,8, 9 ultrasound may be indeterminate. The clinician is left with a patient in whom the pregnancy is probably too early to be seen, but in w h o m ectopic pregnancy cannot be excluded. "Suggestive" ultrasound findings of an adnexal mass or culde-sac fluid could be due to either eco topic pregnancy or corpus luteum cyst rupture. The diagnosis is particularly difficult when a simple adnexal cyst is seen sonographically; an ectopic pregnancy may appear cystic, as may the corpus luteum cyst accompanying a pregnancy of any location. lo Serial quantitative hCG monitoring has been used increasingly to follow the stable patient in whom ectopic pregnancy cannot be excluded by s o n o g r a p h i c i d e n t i f i c a t i o n of the pregnancy. When the hCG level is low for dates or fails to double every two or three days, a nonviable pregnancy can be diagnosed. The location of the pregnancy is in doubt until a d i l a t a t i o n and c u r e t t a g e are performed and tissue confirmation establishes that the pregnancy was intrauterine. If no villi are seen, an ectopic pregnancy must be assumed. Several problems with hCG monitoring in the ED exist: serial levels over several days are required to detect the abnormalities (and 10% of ectopic pregnancies have initially normal doubling times11); prior to 19:4 April 1990

TABLE. Culdocentesis in ectopic pregnancy

Series Brenner, 198013 Tancer, 198114 Weinstein, 198315 Cartwright, 19842 Romero, 19855 Weckstein, 19851 Easley, 198716 Total Percentage

No. of Patients

No. Receiving Culdocentesis


300 556 154 117 243 26 68 1,464

300 274 120 77 163 26 42 1,002 68.4

285 235 98 54 132 19 33 856 85.4

tissue confirmation, the location of a failing pregnancy cannot be determ i n e d by hCG; and q u a n t i t a t i v e hCG testing may not be rapidly or readily available in many hospitals. Thus, serious limitations exist to primary use of quantitative hCG levels in ED patients, who, though stable, are symptomatic and in need of diagnosis at the time of p r e s e n t a t i o n when this is possible. Culdocentesis is usually a very reliable indicator of intraperitoneal blood associated with ectopic pregnancy. A review of culdocentesis literature provides considerable argument for its continued inclusion in our armamentarium in ectopic pregnancy. As can be seen (Table), positive results ( n o n c l o t t i n g blood) are extremely c o m m o n in multiple series over the past 20 years. (A limitation of most series is that culdocentesis is only performed in about two thirds of all p a t i e n t s , and p r o s p e c t i v e studies have not been done to confirm this accuracy in unselected patients with potential ectopic pregnancy.) The high incidence of positive results in stable patients appears to be explained by the pathophysiology of ectopic pregnancy. The growth of the implanted trophoblast within the tubal serosa frequently causes retrograde bleeding into the peritoneal cavity through the fimbriated ends of the fallopian tubes before frank rupture occurs. I n t e r m i t t e n t small bleeds cause the intermittent symptoms (often for a week or more in duration) characteristic of patients with ectopic pregnancy. The blood pools in the cul-de-sac and is accessi19:4 April 1990

Results Serous Indeterminate 0 25 15 8 4 1 3 56 5.6

15 14 7 15 27 6 6 90 9.0

ble through the culdocentesis needle even when frank peritoneal signs are not present. As Romero has demonstrated, in his series of 132 positive culdocenteses, 45% were in patients without peritoneal signs on examination. 5 Dry taps or clotted blood ("indeterm i n a t e " results) are seen in about 10% to 20% of ectopic pregnancy patients in most series (Table). Romero has demonstrated that dry taps are due not to a dry cul-de-sac but to technical difficulties with access to the peritoneal cavity. Such patients usually have significant intraperitoneal blood at laparotomy. Serous results as we found in our two cases are relatively u n c o m m o n (Table). Serous fluid is usually considered a very reassuring "negative" result because a small amount of serous fluid is present in the peritoneal cavity normally, and its aspiration shows that the needle has indeed entered the correct space. While a serous result does not exclude ectopic pregnancy, it argues against an actively bleeding ectopic pregnancy because even 66% of "unruptured" ectopic pregnancies have blood in the cul-de-sac. The physician is normally reassured that ectopic pregnancy is less l i k e l y and that c a t a s t r o p h i c bleeding prior to follow-up studies is less likely (although this is without much scientific basis). One valid reason for the current reluctance to use culdocentesis is that patient discomfort during the procedure is considerable. While culdocentesis is technically easy, it is impossible to adequately anesthetize the mucosa of the posterior cul-deAnnals of Emergency Medicine

Positive Results Nonclotted blood (> 0.5 mL) Pus Negative Results Serous fluid (0.3-5 mL) Indeterminate Results Dry tap Clotted blood (> 0.5 mL)* Serous fluid (> 5 mL) *Unless patient had evidence of severe acute hypovolemia. 1

FIGURE. Culdocentesis interpretation. sac in most patients and certainly not possible to avoid the pain of the peritoneal lining puncture. In addition, pain from the tenaculum can be considerable. If the procedure is to be used more widely, a short-acting IV narcotic would be ideal for allowing efficient culdocentesis without causing undue patient suffering. If positive results are obtained, a family member may be required to sign consent for further procedures, or naloxone may be administered if urgent surgery is required and the patient must consent to further care. Our case reports suggest that the definition of a negative tap needs further clarification. While most authors agree that clear fluid return with a hematocrit of less than 3% to 10% is a negative tap, there is no m e n t i o n of the significance of the volume returned. Cartwright accepts a minimum of 0.3 mL as evidence of correct placement and a negative result, but there are no reports on the meaning of a 10 mL clear return. ~ In both of our cases, tap of the concomitant corpus luteum cyst in the cul-de-sac was interpreted as negative. We propose, based on these cases, that a large volume of serous return be treated as "nondiagnostic" (Figure). If ultrasound is nondiagnostic, laparoscopy should be undertaken in patients with high clinical suspicion for ectopic pregnancy. Our cases should not discourage the physician from performing culdocentesis in the patient with a nondiagnostic ultrasound and a reasonable suspicion for ectopic pregnancy. A l t h o u g h noninvasive procedures have become popular and can be used 409/105

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w i t h m i n i m u m p h y s i c i a n effort i n a b u s y ED, i t is c l e a r f r o m t h e a b o v e discussion that both ultrasound and quantitative hCG levels have limitat i o n s i n s o m e p a t i e n t s . Indeed, s o m e a u t h o r s h a v e s u g g e s t e d t h a t t h e recent trend to avoid culdocentesis in t h e w o r k u p of t h e p a t i e n t w i t h susp e c t e d e c t o p i c p r e g n a n c y h a s led to increased delays in ectopic pregnancy d i a g n o s i s . 12 B e c a u s e a p o s i t i v e c u l d o c e n t e s i s is s e e n e v e n i n t h e m a j o r i t y of s t a b l e e c t o p i c p r e g n a n c y p a t i e n t s , serous culdocentesis provides additional data that allow the physician to s e n d a p a t i e n t h o m e w i t h i n s t r u c tions to return with close follow-up if s y m p t o m s p e r s i s t or i n c r e a s e . I n the patient with a corpus luteum cyst on ultrasound, the physician should entertain the possibility that the cyst has been aspirated, particu l a r l y w h e n a large v o l u m e of s e r o u s f l u i d is o b t a i n e d .

SUMMARY W e p r e s e n t t w o c a s e s of f a l s e - n e g a tive culdocentesis in patients with ectopic pregnancies and coexistent corpus luteum cysts. Culdocentesis can be a safe and very accurate


m e t h o d of d i a g n o s i n g b o t h " u n r u p tured" and ruptured ectopic pregn a n c y , a n d m a y b e v a l u a b l e i n patients with indeterminate ultrasound and quantitative hCG results. We p r o p o s e t h a t large a m o u n t s of s e r o u s fluid returned by culdocentesis should prompt consideration of a large c o r p u s l u t e u m c y s t ( e i t h e r w i t h or w i t h o u t a n e c t o p i c p r e g n a n c y ) a n d should be considered a nondiagnostic tap.

REFERENCES 1. Weckstein LN, Boncher AR, Tucker H, et all Accurate diagnosis of early ectopic pregnancy. Obstet Gynecol 1985;65:393-397. 2. Cartwright PS, Vaughn B, Tnttle D: Culdocentesis and ectopic pregnancy. J Reprod Med 1984;29:88-91. 3. Schwartz RO, DiPietro DL: f~-hCG as a diagnostic aid for suspected ectopic pregnancy. Ob stet Gynecol 1980;56:197-203. 4. Breen JL: A 21 year survey of 654 ectopic pregnancies. Am J Obstet Gynecol 1970; 106:1004-1016. 5. Romero R, Copel J, Kadar N, et al: Value of culdocentesis in the diagnosis of ectopic pregnancy. Obstet Gynecol 1985;65:393-397. 6. Droegemueller W, Herbst AL, Mishell DR, et al: Comprehensive Gynecology. St Louis, CV Mosby, 1987, ]2 470-473. 7. Kadar N, DeVote G, Romero R, et ah Dis-

Annals of Emergency Medicine

eriminatory hCG zone: Its use in the s o nographic evaluation for ectopic pregnancy. Obstet Gynecol 1981;58:156-161. 8. Cacciatore B, Stenman UH, Ylostalo ]2: Comparison of abdominal and vaginal sonography in suspected ectopie pregnancy. Obstet Gynecol 1989;73:770-774. 9. Leach RE, Ory SJ: Modern management of ectopic pregnancy. J Reprod Med 1989;34: 324-338. 10. Romero R, Kadar N, Castro D, et al: The value of adnexal sonogra]2hic findings in the di agnosis of ecto]2ic pregnancy. Am J Obstet G)' necol 1988;158:52-55. 1l. Romero R, Kadar N, Copel JA, et ai: Th

Serous culdocentesis in ectopic pregnancy: a report of two cases caused by coexistent corpus luteum cysts.

Two cases of women with large-volume serous culdocentesis results are presented. Both patients ultimately had ectopic pregnancies diagnosed surgically...
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