22.2 Ovarian Malignancy, Torsion & Fallopian Tubes

Sonographic Red Flags for Malignancy

Ovarian cancer is the deadliest gynecologic malignancy, largely because it presents late, and the sonographer's morphology report often determines whether a mass is watched or removed. Features that raise suspicion include:

• Papillary projections or solid mural nodules, especially when they show internal blood flow on color Doppler
• Thick septations greater than about 3 mm
• A solid or predominantly solid architecture
• Bilaterality of complex masses
• Ascites, peritoneal implants, or omental caking in the upper abdomen
• Persistence or growth on short-interval follow-up

Historically, low-impedance tumor flow (resistive index under 0.4 or pulsatility index under 1.0) was cited as a malignancy marker, but benign structures such as the corpus luteum display identical low-resistance flow, so Doppler indices alone cannot separate benign from malignant disease.

Serous cystadenocarcinoma is the most common malignant epithelial ovarian tumor and typically appears as a large multiloculated cystic mass with thick septations and papillary solid components; its mucinous counterpart contains echogenic locules. Other malignant histologies to recognize include endometrioid and clear cell tumors (often arising in endometriomas), the dysgerminoma — a solid germ cell tumor of young women analogous to seminoma — and the granulosa cell tumor, an estrogen-producing sex cord-stromal tumor that may present with abnormal bleeding or a thickened endometrium. Krukenberg tumors are metastases to the ovaries — classically bilateral, solid, and sometimes moth-eaten in texture — most often from a gastric signet-ring cell primary, with colon and breast as other common sources. Once a suspicious mass is found, the survey should extend beyond the pelvis: look for ascites in the paracolic gutters and Morison pouch, omental caking, peritoneal and liver-surface implants, and enlarged para-aortic nodes, because this documentation shapes staging.

CA-125 is a serum tumor marker with an upper limit of about 35 U/mL. It is most useful in postmenopausal women and for monitoring treatment response, but it is nonspecific — it rises with endometriosis, pelvic inflammatory disease, menstruation, fibroids, and even pregnancy — so it cannot be used alone as a screening test.

Simple Cyst Management

Incidental simple cysts are overwhelmingly benign, and over-referral is itself harmful. Under the 2019 SRU consensus update (which relaxed the older 2010 thresholds), in premenopausal women cysts up to 3 cm are physiologic follicles that need not even be reported; simple cysts of 3-5 cm should be described but need no follow-up; and follow-up is reserved for cysts larger than about 5-7 cm. In postmenopausal women, document any simple cyst over 1 cm, but follow up only those larger than about 3-5 cm — so a 2 cm postmenopausal simple cyst needs no follow-up at all. O-RADS US v2022 similarly classifies a simple cyst under 10 cm as almost certainly benign, with 10 cm the usual trigger for MRI or surgical evaluation. Any cyst with septations, mural nodules, or solid elements falls outside these simple-cyst pathways regardless of size.

Ovarian Torsion

Ovarian torsion is twisting of the ovary on its vascular pedicle, which obstructs venous and lymphatic drainage first. The result is a markedly enlarged, edematous ovary (commonly over 4-5 cm) with peripherally displaced follicles, central echogenic stroma, and often free fluid in the pelvis. Most cases involve an underlying cyst or mass acting as a lead point, and the right ovary is affected more often than the left. It is a surgical emergency — prompt detorsion can salvage the ovary, so the sonographic report must never delay the clinical decision.

Doppler interpretation is the classic exam trap: absent arterial and venous flow strongly supports torsion, but the presence of flow does not exclude it. Dual blood supply from the ovarian and uterine arteries, intermittent or partial twisting, and early presentation can all preserve detectable flow. The whirlpool sign — a twisted, coiled vascular pedicle demonstrated with color Doppler — is the most specific finding when it can be shown. The clinical picture of acute, severe, unilateral pain with nausea and vomiting should drive management even when the Doppler examination looks reassuring.

Fallopian Tubes and Pelvic Inflammatory Disease

The normal fallopian tube is about 10 cm long and is not visualized sonographically unless outlined by fluid or ascites. A fluid-filled, dilated tube — hydrosalpinx — appears as a tubular, sausage- or C-shaped anechoic structure separate from the ipsilateral ovary. Its signs reflect the folded tubal anatomy:

Pyosalpinx is a pus-filled tube: thick walls, echogenic debris, and a fluid-debris level in a febrile patient. When infection obliterates the tissue plane between the tube and ovary, a tubo-ovarian abscess (TOA) forms — a complex, multiloculated adnexal mass with thick irregular walls, internal debris, surrounding hyperemia, and loss of normal architecture. Pelvic inflammatory disease (PID) is the ascending infection that drives this whole spectrum: endometritis and salpingitis progress to pyosalpinx and TOA. Patients present with fever, leukocytosis, pelvic pain, cervical motion tenderness, and discharge; the long-term sequelae are infertility and ectopic pregnancy. Extension of infection to the liver capsule produces Fitz-Hugh-Curtis syndrome (perihepatitis) with right upper quadrant pain and violin-string adhesions.

Technique

Suspected torsion or tubal disease is best evaluated transvaginally. Compare both ovaries side by side for size and echotexture, set the color Doppler gain and pulse repetition frequency low enough to detect slow venous flow, and record spectral waveforms and resistive indices if arterial flow is identified. Sweep laterally from each uterine cornu to separate the tube from the ovary; cine clips help demonstrate whether a cystic structure is tubular (tubal origin) or round (ovarian origin), and gentle probe pressure can show whether the ovary moves independently of an adjacent collection.