The gynaecological causes of acute pelvic pain include haemoperitoneum, infection, abnormal pregnancy, and vascular complications.

Haemoperitoneum may be due to retrograde menstruation, rupture of functional or neoplastic ovarian cysts, or an ectopic pregnancy. It may also follow uterine perforation during the insertion of an intrauterine device or an operation on the uterus, such as dilatation and curettage, or hysteroscopy.

Salpingitis due to sexually transmitted disease is the most common infective gynaecological cause of pelvic pain. Other causes include septic abortion or rupture of a pelvic abscess. In postmenopausal women, pyometra, usually associated with endometrial malignancy, may rarely cause acute pain. Important non-gynaecological infective causes of acute pelvic pain include appendicitis and diverticulitis. Occasionally in women with cystitis, pyelonephritis, or ureteric colic, acute pelvic pain may be the primary complaint; this last diagnosis is especially likely in women with a pelvic kidney. Other less common non-gynaecological causes of acute pelvic pain include regional ileitis and lower-bowel obstruction, due to malignancy, mesenteric occlusion, or pelvic vein thrombophlebitis. Orthopaedic causes include sacroiliac strain, referred pain from a prolapsed intervertebral disc, or degenerative changes in the lumbar spine.

In addition, several complications of early pregnancy may present with acute pelvic pain. These include inevitable abortion, ectopic pregnancy, and rupture of a corpus luteum cyst. In later pregnancy, red degeneration of a fibroid or placental abruption may also cause acute pelvic pain.

Torsion of an ovarian cyst or, more rarely, a pedunculated subserous fibroid is also a cause of acute pelvic pain.

The most important differential diagnoses are acute salpingitis, an ovarian cyst accident, or a tubal ectopic pregnancy, and the most prominent question in the mind of any clinician managing a woman in the reproductive age-group should be ‘does this woman have an ectopic pregnancy?’ Ectopic pregnancy remains an important cause of maternal death and, although this follows sudden collapse in approximately a third of cases, the remaining deaths are potentially avoidable.

The classical presentation of an ectopic pregnancy depends on its site of implantation in the fallopian tube. There is usually amenorrhoea of 6 to 8 weeks' duration, and longer if the pregnancy is situated in the ampullary end of the tube. Pregnancy symptoms are variable and may, or may not, be elicited. The pain, which is due to intraperitoneal bleeding, is usually unilateral and present in the lower abdomen and pelvis. If there is significant intraperitoneal bleeding, the blood may track up under the diaphragm and cause referred shoulder-tip pain. Vaginal bleeding tends to be scanty and dark-brown in colour, and usually begins a few hours after the onset of the pain. Pregnancy symptoms, such as nausea and breast tenderness, may have been present but frequently cease shortly before the onset of pain and bleeding. Factors that predispose to tubal ectopic pregnancy include intrauterine contraceptive devices, the progestogen-only pill, tubal damage following salpingitis or appendicitis, and embryo transfer following in-vitro fertilization. As with acute appendicitis, the presentation is varied and, when suspected, cannot be excluded on the basis of history alone. An ectopic pregnancy can be associated with almost any pattern of bleeding, and the pain may not be unilateral.

Pelvic inflammatory disease, due to salpingitis, is usually but not always bilateral, and may be associated with fever, rigors, and a purulent vaginal discharge. There may also be a history of abnormal vaginal bleeding. The pain tends to be an increasingly severe constant ache, but may become colicky if a pyosalpinx develops causing significant tubal distension. Vomiting tends, paradoxically, to be more common than in women with tubal pregnancies. Predisposing factors include a history of previous pelvic infection, an intrauterine contraceptive device, or a recent change of sexual partner.

Pain associated with torsion of an ovarian tumour, normal adnexum, or a pedunculated fibroid, is usually of sudden onset, confined to one side, and colicky in nature. Vomiting is also common.

Lower abdominal guarding and rebound tenderness indicate significant pelvic pathology, but physical findings in women with acute pelvic pain may be misleading. Unilateral signs usually indicate an ectopic pregnancy, ovarian accident, or extragenital pathology. Bilateral signs commonly indicate pelvic inflammatory disease but do not exclude any of the above diagnoses. The uterus is usually slightly enlarged and softened with an ectopic pregnancy, and this may cause confusion with an early intrauterine pregnancy. The cervix, however, dilates during abortion and the vaginal blood loss is generally heavier. Although pain on movement of the cervix, so-called ‘cervical excitation’ pain, is typical of a ‘leaking’ tubal ectopic pregnancy, it will also be observed whenever there is pus or blood in the pelvis, causing peritonism.

The classic acute presentation of a ruptured ectopic pregnancy involves shock, signs of a significant haemoperitoneum, an profound anaemia. In this situation a pelvic examination is contraindicated as it may cause further, ‘life-threatening’ intra-abdominal haemorrhage. On the other hand, a patient with a chronic ‘leaking’ ectopic pregnancy may occasionally present with severe anaemia, a stable pulse and blood pressure, acute pain, and a chronic pelvic haematocele. Tubal ectopic pregnancies are seldom palpable unless they are of advanced gestation, situated in the ampullary portion of the tube, or are associated with a pelvic haematocele.

The presence of a pelvic mass separate from the uterus usually indicates an ovarian tumour, a pyosalpinx, a tubo-ovarian mass, or occasionally a subserous fibroid. Although fibroids rarely cause acute pelvic pain, pedunculated fibroids may undergo torsion and present a clinical picture of acute colicky pain and vomiting, indistinguishable from that due to torsion of an ovarian tumour. Red degeneration, due to ischaemic necrosis of a fibroid, causes a constant severe ache. It is usually associated with pregnancy but it may also occur in perimenopausal women.

Copious purulent vaginal discharge, visible on speculum examination, suggests a sexually transmitted infection, or possibly a septic inevitable or incomplete abortion. Vaginitis and cervicitis may, however, also cause a profuse infected vaginal discharge and this sign cannot therefore be considered to be indicative of pelvic inflammatory disease.

A fever in excess of 38°C in a woman with acute pelvic pain is usually due to salpingitis, septic abortion, appendicitis, a urinary tract infection, or some other extragenital infection. Lesser degrees of fever may, however, occur with any of the pelvic pathologies.

Basic urinary pregnancy tests are inexpensive and should be the first line of investigation in sexually active women with acute pelvic pain. They will, however, give a negative result in 50 to 80 per cent of tubal ectopic pregnancies. A negative test is therefore an indication for further investigation using one of the more sensitive monoclonal antibody tests which measure urinary &bgr;-human chorionic gonadotropin (&bgr;-hCG). A positive result with this very sensitive technique indicates an absolute need to determine whether the pregnancy is intrauterine or extrauterine; a negative result does not, however, exclude an ectopic pregnancy.

Urine must also be examined microscopically and cultured. It should, however, be remembered that white cells may appear in urine in association with an ovarian accident or appendicitis. In addition, the presence of pyuria does not exclude an ectopic pregnancy! Cervical and high vaginal swabs should be cultured, looking particularly for Chlamydia spp. and Neisseria gonorrhoeae. If Chlamydia culture is not available, then the new slide tests for Chlamydia antigen should be used. If the patient has a pyrexia of more than 38°C, blood cultures should be obtained.

Although a full blood count and erythrocyte sedimentation rate should be performed, these are of limited value as the haemoglobin concentration is rarely reduced in women with an ectopic pregnancy, except where there is massive intraperitoneal bleeding or a pelvic haematocele. In addition, the finding of an elevated white cell count or erythrocyte sedimentation rate is non-specific, as these may be elevated in any of the conditions that cause acute pelvic pain. The erythrocyte sedimentation rate may, however, be useful in monitoring the response of pelvic inflammatory disease to antibiotic therapy. Elevated serum concentrations of antibodies to genital tract pathogens e.g. Chlamydia do not necessarily indicate acute infection and are of minimal diagnostic value in this clinical situation.

Abdominal and vaginal ultrasound scanning is of undoubted value in diagnosing pelvic pathology. Intrauterine pregnancy can be diagnosed before 6 weeks using a vaginal probe, and thereafter with an abdominal transducer. Ultrasound techniques are, however, of limited value for the diagnosis of tubal ectopic pregnancy and, although reports of ‘cystic structures’ in the adnexal regions or evidence of free fluid in the pouch of Douglas may arouse suspicion, a diagnosis of a tubal ectopic pregnancy cannot be made with certainty unless a fetal heart can be seen beating outside the uterine cavity. In addition, the absence of ultrasound evidence of an intrauterine pregnancy in a woman with a positive pregnancy test does not necessarily indicate that the pregnancy is ectopic, as very small amounts of placental tissue in women with a missed or incomplete abortion can produce a positive urinary &bgr;-hCG pregnancy test. Furthermore, it must be emphasized that although identification of an intrauterine pregnancy greatly reduces the likelihood of an ectopic pregnancy, it does not exclude this diagnosis. Ultrasound scanning of the pelvis and lower abdomen, by experts using high-resolution equipment, is, however, extremely valuable for the diagnosis of ovarian cysts, fibroids, and missed abortion, and for identifying viable intrauterine pregnancies.

Whenever there is any doubt, a laparoscopy must be performed in order to make a definitive diagnosis.

The decision to perform a laparoscopy is dictated by the clinical situation and the speed with which the above investigations can be performed. When there is an obvious haemoperitoneum or the patient is shocked, an urgent laparotomy is indicated, as laparoscopy could be hazardous for a patient in this condition and could delay the arrest of bleeding. On the other hand, if the woman's condition is stable and technical difficulties are anticipated because of obesity, or a history of gross adhesions, a conservative course may be preferable. If the diagnosis is in doubt and a laparoscopy is either contraindicated or laparoscopic equipment is not available, then a laparotomy, or possibly a minilaparotomy using a Cusco speculum, should be performed. It must be emphasized that an examination under anaesthesia will not exclude an ectopic pregnancy and has no part in the modern management of this condition. In addition, provided that appropriate operative facilities are available, there can be no justification for performing a culdocentesis.

A careful and methodical approach should be used when assessing the pelvis and abdominal cavity laparoscopically. The anterior and posterior surfaces of the uterus should be inspected and both fallopian tubes visualized throughout their length. Minor degrees of inflammation of the fallopian tubes may, however, prove difficult to distinguish from the hyperaemia induced by the carbon dioxide used to insufflate the abdominal cavity. The ovaries should be lifted up to enable the whole surface of each to be inspected and the pouch of Douglas should be examined carefully to exclude endometriosis or adhesions. In addition, the presence of any free fluid or blood should be noted. If there is evidence of infection, fluid should be aspirated and swabs taken from the fallopian tubes for bacteriological examination. The parietal peritoneum should be examined for adhesions and, whenever possible, the appendix should be identified and examined throughout its length. The gallbladder should also be inspected to exclude cholecystitis and the perihepatic area should be examined to exclude adhesions due to the Fitz-Hugh and Curtis syndrome (chlamydial perihepatitis). It is vital that the findings are documented accurately for future reference.

When a laparoscopy is performed in women with acute pelvic pain, approximately 35 per cent will have acute or chronic pelvic inflammatory disease; 20 per cent will have an ectopic pregnancy; 15 per cent, an ovarian cyst; 5 per cent, adhesions not associated with pelvic inflammatory disease; and 2 per cent, appendicitis. In the remaining cases, no cause will be identified.

When a tubal ectopic pregnancy is diagnosed and active bleeding is suspected, the primary concern is to achieve haemostasis. A laparotomy should therefore be performed, without delay, through a low transverse suprapubic incision, and haemostasis achieved as rapidly as possible by applying an artery clamp on either side of the ectopic pregnancy. The affected tube should then either be removed completely or partially, depending on the site of the ectopic pregnancy and the extent of the tubal damage. There is, however, no correct way to proceed once the ectopic pregnancy has been removed. Ideally, a minimum amount of tube should be removed and the cut ends ligated so as to allow a tubal reanastomosis at a later date. It is best to resist the temptation to perform an adhesolysis or further tubal surgery at the time of the ectopic pregnancy, as conditions at the time of the acute episode mitigate against a successful outcome. Although traditional treatment of a tubal ectopic pregnancy involves a laparotomy and either a partial or total salpingectomy, or occasionally a salpingo-oophorectomy, more conservative forms of treatment which aim to conserve tubal function are nowadays considered to be preferable if the ectopic pregnancy is still intact. These include ‘milking’ the ectopic out of the ampullary end of the tube when possible or, if the ectopic is in the midportion of the tube, performing a ‘linear salpingostomy’, in which the tubal pregnancy is removed through a vertical incision on the antimesenteric border of the fallopian tube overlying the site of the ectopic. Where the necessary equipment and expertise are available, this latter procedure can also be performed under endoscopic control, thus avoiding the need for a laparotomy and resulting in a more rapid postoperative recovery. Whether the procedure has been performed endoscopically or by laparotomy, it is advisable, at the conclusion, to wash out the peritoneal cavity with warm isotonic saline, thus minimizing the likelihood of postoperative ileus and adhesion formation. Prophylactic antibiotics should be considered postoperatively.

Acute or chronic pelvic infection should be treated initially with intravenous antibiotics, even if there is no evidence of a bacteraemia or septicaemia. A combination of metronidazole, a third-generation cephalosporin, and doxycycline should be used initially, pending the bacteriological results obtained from the cervical, vaginal, and fallopian tube swabs, peritoneal fluid, and blood cultures, regardless of the suspected aetiology. Subsequent treatment should be based on the antibiotic sensitivities, but must include an antichlamydial agent, such as tetracycline or erythromycin. Ideally, antibiotic therapy should be continued for at least a month, rotating through two or three different combinations of antibiotics. If a tubo-ovarian mass or abscess is observed during laparoscopy, this is not an indication for surgery. A laparotomy should only be performed if the patient has septic shock or if the mass fails to reduce in size with effective antibiotic therapy. If a pelvic abscess is situated in the pouch of Douglas, it may be more appropriate to drain this by making an incision through the posterior vaginal fornix rather than performing a laparotomy. The patient's sexual partner should be advised to attend a genitourinary medicine clinic for screening and appropriate treatment.

Rocker I. Gynecological pain. In: Rocker I, ed. Pelvic pain in women—diagnosis and management. Berlin: Springer-Verlag, 1990: 103–31.

Weingold AB. Pelvic pain. In: Kase NG, Weingold AB, eds. Principles and practice of clinical gynecology. New York: John Wiley and Sons, 1983: 497–526.