Cannula fracture in first trimester abortion: a case report and survey of NAF providers

1. Introduction 

First trimester surgical abortions are considered safe procedures. Hakim-Elahi reported that the overall complication rate for first trimester procedures is 9 per 1000 [1]. In his study of 170,000 abortions, there were no reports of cannula fractures [1]. A review of the medical literature using MedLine located only a letter of correspondence and its reply in 1970 on “accidental fracture of a curette” [2], [3]. The keywords used for the MedLine search included first trimester abortion complications, curette, cannula, sterilization, fracture, fatigue, plastic, and foreign body. In total, three plastic cannula fractures during first trimester surgical abortions have been previously reported [2], [3].

Prior to this case, we had been unaware of this complication. The referring abortion clinic used Berkeley Medevices Inc.™ disposable flexible cannulas for the majority of abortions under 11 weeks gestation. While this clinic does not resterilize and recycle their cannulas, many clinics in the United States do resterilize to limit costs. The practice of resterilizing plastic curettes may cause plastic fatigue and increase the incidence of fracture. A survey was developed to discover the frequency of cannula fracture and the prevalence of cannula resterilization and reuse among the members of the National Abortion Federation (NAF).

2. Case report 

A nulliparous woman at 9 weeks gestation by last menstrual period and ultrasound presented to a free-standing abortion clinic for a surgical abortion. The patient was healthy and had no history of any prior cervical trauma. The cervix was dilated to 8 mm. Placement of the cannula was difficult and subsequently it could not be easily removed. In extracting the cannula, the tip accidentally fractured leaving a foreign body within the cervix. No disruption of the pregnancy occurred. The cannula tip could not be dislodged under local anesthesia and the patient was transferred to the closest hospital for an exam under general anesthesia. During transport, the patient changed her mind about terminating the pregnancy. The tip was localized by ultrasound but could not be removed without compromising the pregnancy (Fig. 1). One month later, a pelvic X-ray could not visualize the foreign body. The patient had not noticed passing the cannula tip. She went on to have an uncomplicated term delivery and the cannula tip was never found. A postpartum pelvic computed tomography scan showed no foreign body.

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Fig. 1. Pelvic ultrasound performed immediately after cannula fracture. Echogenic focus indicated by arrow, consistent with cannula tip.

3. Materials and methods 

Consent to survey NAF members was obtained from the National Abortion Federation research committee. A one-page survey was sent with a cover letter and a prestamped return envelope. Each provider was assigned a number for an anonymous response. If providers desired not to participate, they were asked to return their surveys blank. If a response was not received by 3 weeks, another survey was sent. Up to three mailings were sent to achieve an adequate response rate. Several providers received repeat mailings because of a delay in returning the original survey. Three providers completed and returned all three mailings. For those providers who returned more than one survey, only the data in the first returned survey were analyzed.

The survey addressed the following issues: an estimation of the number of first trimester abortions completed by the provider in 1 year, brand and type of cannulas used, whether or not cannulas were resterilized and reused, type of resterilization of cannulas (if any), number of fractures experienced by the provider (any type) and complications from the fracture, specifically a foreign body. Questions were arranged by fill-in blanks, ordinal and numerical scales. Student’s t-tests and chi-square tests were utilized for continuous and categorical data, respectively (SPSS Inc, Chicago, IL, USA).

4. Results 

A total of 260 surveys were mailed. Of these, four surveys were duplicates and two surveys were returned with no forwarding address, decreasing the actual number of surveys sent to 254. After three mailings, 181 surveys were returned for a final response rate of 71%. Data were obtained from only 173 surveys because five surveys were from sites where no pregnancy terminations are performed and three providers desired not to participate and returned their surveys blank.

Providers estimated that they performed 50 to 10,000 (mean = 1648, SD = 1398) first trimester surgical abortions per year. The majority of providers reported using only rigid cannulas (54%) or a combination of both flexible and rigid (33%). A variety of cannula manufacturers are used but Medgyn Products Inc.™ and Berkeley Medevices Inc. were the most commonly reported, at 25% and 26%, respectively.

There were 16 positive responses to the question “Has a cannula broken during a procedure” (9%). Rigid cannulas were the most common cannulas that fractured (81%). Some of these sites reported more than one cannula fracture, for a total of 40 estimated fractures for the entire group. However, only one case of fracture resulted in a retained foreign body. In that event, the cannula tip fractured within the uterine cavity and was immediately retrieved with further dilation and suction curettage.

Ten percent of NAF members (18/173) resterilize and reuse cannulas. The methods used to resterilize cannulas include gas (50%), soaking solution (39%) and autoclave (11%). No significant difference in breakage was seen between the sites reporting resterilization (3/18, 17%) and those using a cannula only once (13/155, 8%, p = 0.25). However, all three sites that practiced resterilization and reported a breakage used a gas sterilization technique.

The survey provided additional space for provider written comments. In addition to those reporting intra-procedure cannula fractures, many providers described cannula fracture prior to the procedure. Most of these fractures were located at the point were the hub meets the cannula shaft and not at the tip.

5. Discussion 

Of the 1.1 million abortions performed in the United States each year, approximately 90% are in the first trimester [4]. Complications in first trimester surgical abortion are uncommon. This report provides additional evidence for the safety of the procedure by documenting that cannula breakage is a rare event not associated with significant complications. Only three cases of broken cannulas resulting in a retained foreign body have been previously reported [2], [3]. This case report and our survey of NAF members result in an additional 42 reported cases of cannula fracture. Only our consultation and one NAF reported event, however, resulted in a retained foreign body. In our case, after failed attempts at removal, the tip of the cannula was evidently expelled from the uterus and the pregnancy continued to full-term without complication. The second reported incident resulted in a successful therapeutic abortion with the cannula tip being easily removed after further dilation and repeat suction.

We had concerns that repeated use of cannulas or the resterilization process might weaken the material and increase the risk of fracture. Our results did not support this hypothesis. Although 10% of respondents admitted to resterilization, the rate of reported breakage (9%) was not significantly higher in this group than at sites practicing single use. Attempts were made to reach cannula manufacturers for comments. One manufacturer (Medgyn Products Inc.) responded to our query and replied that they have no data on high temperature sterilization (i.e., autoclave) and its effects on their cannulas. They expressed concern about the potential for plastic fatigue. International reproductive health organizations promote single cannula use or high-level disinfectant of plastic instruments with steam and chemical soaking [5]. Due to small numbers, we were not able to identify a specific brand of cannula, type of cannula or resterilization method that significantly increases the risk of fracture. Of note, however, all breakage events recorded in the resterilization group occurred at clinics utilizing a gas sterilization technique.

The strengths of this study include the sample population and the excellent response rate of 71%. The NAF membership includes physicians who perform a large proportion of abortions in this country and NAF strongly supports abortion research. Thus, this survey probably represents a significant percentage of the experience with cannula fracture in the United States.

There are limitations to this study. The survey was designed to gather descriptive information. It was retrospective and based on the provider’s ability to recall past events. Providers were not specifically questioned about their vigilance of cannula inspection prior to use. To gather true incidence data, a prospective study would need to be developed to track cannula breakage, resterilization and reuse rates and the method of sterilization. Nevertheless, this is the first attempt to collect this information from abortion providers in the United States.

It appears that cannula fracture occurs rarely during first trimester surgical abortion procedures involving suction curettage with plastic cannulas. Although our results do not establish the safety of resterilization of plastic cannulas, the risk of complications due to breakage of reused devices appears to be small. Research leading to an optimal technique and protocol for resterilization of cannulas could reduce costs and improve access to abortion, particularly in developing nations.