Ultrasound for diagnosing acute salpingitis: a prospective observational diagnostic study

Abstract

What are the diagnostic benefits of using ultrasound in patients with a clinical suspicion of acute salpingitis and signs of pelvic inflammatory disease (PID)? In patients with a clinical suspicion of acute salpingitis, the absence of bilateral adnexal masses at ultrasound decreases the odds of mild-to-severe acute salpingitis about five times, while the presence of bilateral adnexal masses increases the odds about five times. PID is difficult to diagnose because the symptoms are often subtle and mild. The diagnosis is usually based on clinical findings, and these are unspecific. The sensitivity and specificity of ultrasound with regard to salpingitis have been reported in one study (n = 30) of appropriate design, where most patients had severe salpingitis (i.e. pyosalpinx) or tubo-ovarian abscess. This diagnostic test study included 52 patients fulfilling the clinical criteria of PID. Patients were recruited between October 1999 and August 2008. The patients underwent a standardized transvaginal gray scale and Doppler ultrasound examination by one experienced sonologist (index test) before diagnostic laparoscopy by a laparoscopist blinded to the ultrasound results. The final diagnosis was determined by laparoscopy, histology of the endometrium and other histology where relevant (reference standard). Of the 52 patients, 23 (44%) had a final diagnosis unrelated to genital infection, while the other 29 had cervicitis (n = 3), endometritis (n = 9) or salpingitis (n = 17; mild n = 4, moderate n = 8, severe, i.e. pyosalpinx n = 5). Bilateral adnexal masses and bilateral masses lying adjacent to the ovary were seen more often on ultrasound in patients with salpingitis than with other diagnoses (bilateral adnexal masses: 82 versus 17%, i.e. 14/17 versus 6/35, P = 0.000, positive likelihood ratio 4.8, negative likelihood ratio 0.22; bilateral masses adjacent to ovary: 65 versus 17%, i.e.11/17 versus 6/35, P = 0.001, positive likelihood ratio 3.8, negative likelihood ratio 0.42). In cases of salpingitis, the masses lying adjacent to the ovaries were on average 2-3 cm in diameter, solid (n = 14), unilocular cystic (n = 4), multilocular cystic (n = 3) or multilocular solid (n = 1), with thick walls and well vascularized at colour Doppler. In no case were the cogwheel sign or incomplete septae seen. All 13 cases of moderate or severe salpingitis were diagnosed with ultrasound (detection rate 100%, 95% confidence interval 78-100%) compared with 1 of 4 cases of mild salpingitis. Three of six cases of appendicitis, and two of two ovarian cysts were correctly diagnosed with ultrasound, and one case of adnexal torsion was suspected and then verified at laparoscopy. The sample size is small. This is explained by difficulties with patient recruitment. There are few cases of mild salpingitis, which means that we cannot estimate with any precision the ability of ultrasound to detect very early salpingitis. The proportion of cases with salpingitis of different grade affects the sensitivity and specificity of ultrasound, and the sensitivity and specificity that we report here are applicable only to patient populations similar to ours. The information provided by transvaginal ultrasound is likely to be of help when deciding whether or not to proceed with diagnostic laparoscopy in patients with symptoms and signs suggesting PID and, if laparoscopy is not performed, to select treatment and plan follow-up.