A purse-string approach to laparoscopic cornuostomy for interstitial ectopic pregnancy. This video will review surgical techniques for tissue dissection in interstitial ectopic pregnancies and demonstrate a novel approach to resection aimed at minimising surgical morbidity and improving haemostasis.
Interstitial Ectopic Pregnancy
An interstitial ectopic refers to a pregnancy implanted in the proximal fallopian tube where it passes through the myometrium. Although they represent a small percentage of all ectopics, as many as half present with rupture, with an overall mortality of 2%. This necessitates early identification and intervention.
The diagnostic challenge for interstitial ectopics is in distinguishing them from eccentrically located intrauterine pregnancies. An interstitial line sign and surrounding myometrium of less than 5mm are suggestive of an interstitial ectopic. Surrounding endometrium is consistent with an eccentrically located IUP.
While conservative management with methotrexate may be appropriate for a stable patient with an early pregnancy, and an unstable patient may require aa hysterectomy, laparoscopic cornual resection, or cornuostomy, is now the surgival approach of choice for most patients.
Four-Step Purse-String Technique
We propose a four-step approach using a purse-string technique for improved haemostasis and ease of cornuostomy. In step one, we isolate the pregnancy with a salpingectomy on the affected side and ligation of the utero-ovarian ligament. In step two, we circumferentially perform a running suture around the pregnancy to create a purse string. Vasopressin is injected into the surrounding myometrium. In step three, cautery is used to create an incision along the distended uterine surface, and the pregnancy is resected. In the final step, we repair the uterine defect.
First Case Example
Our first case is a healthy 36-year-old G5P1 woman who presented to the emergency department at eight weeks five days gestational age with first-trimester bleeding. We will now demonstrate the purse-string approach.
Step one, isolate the pregnancy. A salpingectomy is performed on the affected side using ligasure along the mesosalpinx. The utero-ovarian ligament is then desiccated and cut.
Step two, ensuring haemostasis. Using a zero-gauge absorbable monofilament suture, a running stitch is applied circumferentially around the pregnancy at the equatorial line. The purse string is then cinched down tight and tied. Appropriate tension should cause serosal indentations as seen here. 20 units of vasopressin in 100cc of normal saline is then injected into the myometrium.
Step three, resection. Using a monopolar L-hook electrode, a linear transverse incision is made at the apex of the pregnancy. The underlying myometrium is then incised, and the products of conception are removed using traction and a blunt-tipped ligasure. Areas of redundant myometrium are excised where necessary, also using the ligasure.
As you can see, using a transverse incision in this manner has allowed for optimal exposure of the pregnancy while still ensuring preservation of sufficient myometrium for the subsequent repair. Here, communication of the myometrium with the endometrial cavity is demonstrated by the metallic surface of the uterine manipulator.
Step four, closure. Using a zero-gauge absorbable braided suture, the endometrial defect is closed separately. Attention is then turned to the more superficial layers. Using a self-locking barbed suture, the myometrium is then reapproximated. This can be performed in layers if necessary, including the serosal layer. Either a baseball stitch or a running continuous technique can be used. The suture is then cut flush with the serosa, and the needle is removed from the patient’s abdomen. Finally, Interceed is applied to the serosa to reduce adhesions.
Second Case Example
Our second case demonstrates the same technique, but applied in a more challenging context. This 35-year-old woman presented at a more advanced gestational age with a medical history that presented challenges for mobilisation of the uterus, and risk factors for significant intraabdominal bleeding. Ultrasound showed a clear ring of myometrium surrounding the pregnancy, confirming the diagnosis. Another view demonstrates the advanced gestational age. Before beginning the cornuostomy, visualisation is optimised by performing a myomectomy on the large interior pedunculated fibroid. A free and braided absorbable suture is introduced and wrapped around the base of the fibroid. An extracorporeal Roeder’s knot is then tied, and the knot is cinched down tightly.
Using the L-hook, a simple myomectomy is performed by creating a linear incision above the suture line. Having freed the fibroid, the distortion from the pregnancy is clearly seen.
Step one, isolating the pregnancy. The mesosalpinx is transected on the affected side with the ligasure for better visualisation, and the utero-ovarian ligament is cauterised and cut. A salpingectomy is then performed.
Step two, ensuring haemostasis. Once again, at the equatorial line, a purse-string suture is run circumferentially around the pregnancy using a zero-gauge absorbable monofilament suture. And intracorporeal knot is tied and cinched down tightly. Vasopressin is then injected distal to the suture line, noting serosal blanching.
Step three, resection. Using the monopolar L-hook, a vertical incision is made in this case to allow for better triangulation due to the previously noted anatomical distortion. Using a combination of blunt dissection and cautery, the gestational sac is gently exposed and an amniotomy is performed. The pregnancy is then expressed from the cavity. The ligasure is then used to excise the gestational sac and further redundant myometrium.
Step four, closure. Using a self-locking barbed suture, the myometrial defect is again repaired in the layered approach. As you can see, the linear incision created in both cases results in some redundancy of myometrium when compared to a circumferential incision around the pregnancy. However, the additional layers create a more robust free approximation than the thinner overlying layer a circumferential approach would create.
In summary, our four-step approach highlights a novel technique for surgical management of an interstitial ectopic pregnancy. The purse-string suture is a useful tool in preventing significant bleeding and allows for interstitial ectopics to be excised with a minimally invasive cornuostomy, even in cases of significant anatomical distortion.