Images in GYN Ultrasound

“Cogwheel” and other signs of hydrosalpinx and pelvic inclusion cysts

Third of 4 parts on cystic adnexal pathology

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These types of cysts do not require further imaging if diagnosis is certain. When can you be confident with the final diagnosis? These authors offer several imaging cases demonstrating indicative factors on 2- and 3-dimensional ultrasonography.



Ultrasonography is the preferred imaging method to evaluate most adnexal cysts. Most types of pelvic cyst pathology have characteristic findings that, when identified, can guide counseling and management decisions. For instance, simple cysts have thin walls, are uniformly hypoechoic, and show no blood flow on color Doppler. Endometriomas, on the other hand, demonstrate diffuse, low-level internal echoes on ultrasonography.

In parts 1 and 2 of this 4-part series on adnexal pathology, we presented images detailing common benign adnexal cysts, including:

In this part 3, we detail imaging for hydrosalpinx and pelvic inclusion cysts. In part 4 we will consider cystadenomas and ovarian neoplasias.


These cysts are caused by fimbrial obstruction and result in tubal distention with serous fluid. A hydrosalpinx may occur following an episode of salpingitis or pelvic surgery.

Sonographic features diagnostic for hydrosalpinx include a tubular or S-shaped cystic mass separate from the ovary, with:

  • “beads on a string” or “cogwheel” appearance (small round nodules less than 3 mm in size that represent endosalpingeal folds when viewed in cross section)
  • “waist sign” (indentations on opposite sides)
  • incomplete septations, which result from segments of distended tube folding over/adhering to other tubal segments

Levine and colleagues noted that 3-dimensional imaging may be helpful when the diagnosis is uncertain.1

When a mass is noted that has features classic for hydrosalpinx, the Society of Radiologists in Ultrasound 2010 Consensus Conference Statement recommends1:

  • no further imaging is necessary to establish the diagnosis
  • frequency of follow-up imaging should be based on the patient’s age and clinical symptoms

In FIGURES 1 through 6 below (slides of image collections), we present 5 cases, including one of a 45-year-old patient presenting with chronic pelvic pain who was found to have bilateral hydrosalginges and right-sided tubo-ovarian complex.

pelvic inclusion cysts

Pelvic/peritoneal inclusion cysts, or peritoneal pseudocysts, are typically associated with factors that increase the risk for pelvic adhesive disease (including endometriosis, pelvic inflammatory disease, or prior pelvic surgery).

Classic sonographic features of pelvic inclusion cysts are:

  • cystic mass, usually with septations/loculations
  • the mass follows the contour of adjacent organs
  • ovary at edge of the mass or sometimes suspended within it
  • with or without flow in septation on color Doppler

When a mass is noted that has features classic for a peritoneal inclusion cyst, the US Society of Radiologists in Ultrasound recommends that1:

  • no further imaging is necessary to establish the diagnosis (although further imaging may be needed if the diagnosis is uncertain)
  • the frequency of follow-up imaging should be based on the patient’s age and clinical symptoms

In FIGURES 7 through 22 below (slides of image collections), we present several cases that demonstrate pelvic inclusion cysts on imaging. One case involves a 25-year-old patient presenting for 2- and 3-dimensional pelvic imaging due to infertility. She had a history of laparoscopic left ovarian cystectomy, right paratubal cystectomy, and lysis of adhesions. She was found to have a pelvic inclusion cyst and an endometrioma in the left ovary.

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Laparoscopic ureterolysis: Techniques and approaches for ureter identification and dissection

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