Isolated fallopian tube torsion (IFTT) is a rare cause of acute abdominal pain in adolescents. Its preoperative diagnosis is often challenging because imaging findings are usually nonspecific. Here we report the case of a 16-year-old girl with IFTT that closely mimicked a functional ovarian cyst. The patient, who had no history of abdominal surgery or pelvic infection, presented with persistent left lower quadrant pain. Initial computed tomography and ultrasonography showed a 30-mm simple cyst without signs of a twisted vascular pedicle, and a functional ovarian cyst was suspected. Her pain persisted, and on day 5 repeat ultrasonography again demonstrated the same simple cyst as at the initial visit, but the left ovary was clearly visualized separately, raising suspicion of a tubal origin. Diagnostic laparoscopy was performed, revealing a 1080° counterclockwise torsion of the left fallopian tube with necrosis, while the ovary appeared normal. As detorsion failed to restore color, a left salpingectomy was performed. Histopathology confirmed torsion secondary to hydrosalpinx. The postoperative course was uneventful, and the patient has remained symptom-free for one year. This case demonstrates that IFTT can occur even in adolescents without risk factors. Identifying a normal ovary on ultrasonography is crucial for suspecting IFTT, and early diagnostic laparoscopy is essential for confirming the diagnosis and preserving future fertility.
Isolated fallopian tube torsion (IFTT) is a rare gynecological emergency in which the fallopian tube twists on its own axis without involvement of the ipsilateral ovary [1, 2]. Reported risk factors include prior abdominal surgery and pelvic infection. Consequently, IFTT most often occurs in women of reproductive age and is rarely encountered in adolescents [2]. Imaging findings such as fallopian tube dilatation and the “whirlpool sign” have been described as important diagnostic clues; however, they are not consistently present, making early diagnosis challenging [3].
Here we report a case of IFTT in a 16-year-old adolescent girl with no prior history of surgery or infection. The lesion appeared as a 30-mm simple cyst, which was difficult to distinguish from a functional ovarian cyst. Awareness of such cases is clinically important to avoid misdiagnosis and to enable timely surgical intervention.
A 16-year-old girl with no history of abdominal surgery, pelvic infection, or sexual activity presented to our emergency department with left lower abdominal pain. Her vital signs were stable, and physical examination revealed only mild tenderness in the left lower quadrant without signs of peritoneal irritation. Laboratory tests showed mild leukocytosis without elevation of C-reactive protein. Computed tomography (CT) demonstrated a 30-mm simple cyst in the left pelvis and mild thickening of the small intestinal wall (Figure 1A). Although she lacked gastrointestinal symptoms such as nausea, diarrhea, or fever, she was discharged with a diagnosis of acute enteritis and left functional ovarian cyst.
The patient was referred to our gynecology department the next day because of ongoing left lower quadrant pain. Transrectal ultrasonography revealed a 30-mm simple cyst in the left pelvis. Contrast-enhanced CT showed no remarkable changes compared with the initial visit (Figure 1B). Because the cyst was small (30-mm) and its morphology was suspected to be a functional cyst, she was again diagnosed with acute enteritis, and follow-up was planned.
A: On day 1, a 30-mm unilocular cyst with a small amount of ascites was observed.
B: On day 2, no significant interval changes were detected.
The patient returned with continued abdominal pain on the fifth day. Transrectal ultrasonography again demonstrated a 33-mm unilocular cyst, similar to the findings on the first and second visits. For the first time, however, the left ovary was separately visualized and appeared normal (Figure 2). Based on this finding, the possibility was raised that the pain originated from the fallopian tube rather than the ovary. Therefore, diagnostic laparoscopy was performed.
A: A 33-mm simple cyst was observed in the left pelvis.
B: The normal left ovary was visualized close to the cyst.
Intraoperatively, the left fallopian tube was twisted 1080° counterclockwise (Figure 3A). An approximately 30-mm cystic lesion was identified at the fimbrial end of the left fallopian tube, suspicious for hydrosalpinx. The cyst was darkly discolored, suggesting necrosis (Figure 3B). The left ovary was normal in appearance (Figure 3C). Detorsion was attempted and observed for 10 minutes; however, there was no significant improvement in color. Preservation of the tube was not feasible, and a left salpingectomy was performed. Histopathological examination confirmed hydrosalpinx as the underlying cause of torsion (Figure 3D). The postoperative course was uneventful, and the patient was discharged on postoperative day 3. She has remained symptom-free during 1 year of follow-up.
A: A 1080° counterclockwise torsion of the left fallopian tube was observed.
B: An approximately 30-mm cystic lesion was identified at the fimbrial end of the left fallopian tube, suspected to be hydrosalpinx. The cyst was darkly discolored, suggesting necrosis.
C: A normal left ovary.
D: A postoperative macroscopic photograph of the resected left fallopian tube.
This case posed diagnostic challenges for two key reasons. First, IFTT occurred in an adolescent with no history of sexual activity, prior abdominal surgery, or pelvic infection, which are among the recognized risk factors. Second, the detected 30-mm cyst mimicked a functional ovarian cyst, making preoperative diagnosis difficult. These features highlight the importance of considering IFTT even in patients without typical risk factors.
Isolated fallopian tube torsion (IFTT) is an uncommon cause of acute abdominal pain, with an estimated incidence of 1 in 1.5 million women [1, 4]. Reported risk factors include prior abdominal surgery and pelvic infection; therefore, IFTT most commonly occurs in women of reproductive age, particularly between the ages of 18 and 45 [2]. The incidence in pediatric and adolescent populations is not well established because of its rarity, and cases are often misdiagnosed as ovarian torsion or appendicitis [3, 5]. Paratubal or paraovarian cysts are the most frequently reported causes in this age group [2, 5]; in our case, however, neither intraoperative findings nor histopathological examination revealed any such cysts. Instead, hydrosalpinx was identified as the underlying lesion. It was unclear whether the hydrosalpinx was preexisting or had developed secondary to torsion. Risk factors for hydrosalpinx include prior pelvic inflammatory disease, tubal surgery, and endometriosis [2]. Because our patient had none of these risk factors, and no adhesions that could serve as a fixation point were observed intraoperatively, we consider that a congenital anomaly or subclinical inflammation may have led to the development of hydrosalpinx. This case underscores the possibility that IFTT can occur even in adolescents without recognized risk factors. Therefore, it should be considered in the differential diagnosis of acute abdominal pain in this age group.
Preoperative diagnosis of IFTT is difficult. Previous studies have described characteristic imaging findings, including a tubular cystic structure, thin walls with septations and internal echoes, and a normal ovary separate from the mass [6–9]. Additional radiologic signs such as the “whirlpool” or “beak” sign on CT or MRI may also support the diagnosis by indicating a twisted vascular pedicle [3, 10]. In our case, however, most of these findings were absent except for the separate visualization of a normal ovary. The cyst was only 30 mm and appeared unilocular, mimicking a functional ovarian cyst. On the first and second visits, the left ovary was not visualized, but on the fifth day it was clearly identified apart from the cyst. This raised the possibility of a tubal rather than ovarian origin. When evaluating a patient with abdominal pain and a small cyst suspected to be a functional ovarian cyst, it is important to confirm the presence of a normal ovary on ultrasonography and to consider IFTT. When IFTT is suspected, diagnostic laparoscopy should be performed to avoid delayed diagnosis.
Treatment options for IFTT include detorsion and salpingectomy [2]. Salpingectomy was performed in the present case because the color of the left fallopian tube did not improve after detorsion, and re-torsion occurred intraoperatively soon after the tube was untwisted. In cases of ovarian torsion, detorsion followed by a secondary evaluation is often recommended to preserve ovarian function [11]. However, because the fallopian tube has a relatively limited vascular supply compared with the ovary, the feasibility of tubal preservation is strongly influenced by the time from symptom onset to diagnosis [2, 12]. Indeed, previous studies have demonstrated that patients with symptom duration longer than one day are significantly more likely to require salpingectomy [5, 13]. Moreover, approximately 70% of young patients reportedly undergo salpingectomy due to delayed diagnosis [2]. As tubal preservation is crucial for maintaining future fertility, clinicians should consider the possibility of IFTT in young women presenting with lower abdominal pain and pursue prompt diagnosis and timely surgical intervention.
In conclusion, IFTT can occur in adolescents without risk factors. In our case, the lack of specific imaging findings made early diagnosis challenging. Careful confirmation of a normal ovary on ultrasonography is important when IFTT is suspected, and diagnostic laparoscopy remains essential for confirming the diagnosis and preserving future fertility.
Not Applicable.
None to declare.
The authors report no conflicts of interest.
All data generated or analyzed during this study are included in this published article.
Conceptualization: Eito Kishimoto, Shota Higami.
Investigation: Eito Kishimoto.
Supervision: Kiyoshi Yoshino.
Writing – original draft: Eito Kishimoto, Shota Higami.
Writing – review & editing: Sayumi Hashiwaki, Ruka Takedomi, Shota Higami, Yasuyuki Kinjo, Tomoko Kurita, Kiyoshi Yoshino.
Informed consent was obtained from the patient for the publication of information relating to them.
