<h3>Study Objective</h3> To demonstrate surgical techniques for approaching an advanced case of endometriosis in a patient with a congenital uterine anomaly, large pelvic mass, and severe adhesive disease. <h3>Design</h3> A step-by-step explanation of the surgery. <h3>Setting</h3> Community Based Teaching Hospital, Operating Room. <h3>Patients or Participants</h3> 33-yo G0 with known unicornuate uterus with non-communicating uterine horn, dysmenorrhea, suspected endometriosis, infertility, congenital absence of right kidney. <h3>Interventions</h3> Chromotubation was first performed to evaluate if the patient had patent fallopian tubes. The pelvic mass was then decompressed and drained revealing multiple right ovarian cysts. Anatomical landmarks were identified with a retroperitoneal dissection and extensive lysis of adhesions. The bladder was backfilled intermittently to help identify surgical planes. A Keith needle was temporarily placed in the abdomen to elevate the pelvic mass and aid in visualization. The pelvic mass and non-communicating uterine horn were resected. Hemostasis was achieved with electrocautery and suturing. Endometriotic implants in the pelvis and diaphragm were fulgurated and an appendectomy was performed due to extensive damage from endometriosis. All specimens were placed in a bag and removed through the umbilical port site. Post-operatively, the patient was started on progesterone therapy. <h3>Measurements and Main Results</h3> Successful completion of surgery, no complications, the patient reported improvement in her symptoms. <h3>Conclusion</h3> When dealing with severe adhesive disease, abnormal anatomy, and limited space due to a pelvic mass it is key to approach these cases in a stepwise fashion. Visualization can be optimized via temporary measures such as using a Keith needle. If irregular anatomy is noted, landmarks can be identified via the retroperitoneal dissection.