• Participants must have suspected or confirmed clinically advanced stage (III-IV, defined as disease outside of the pelvis) ovarian, fallopian tube, or peritoneal cancer. If a patient has suspected ovarian cancer but final histologic analysis does not show evidence of ovarian cancer, the patient will be removed from the study and replaced.

• Participants must meet one of the following clinical categories:

‣ Cohort 1: Patients with a new or suspected diagnosis of ovarian cancer who are deemed surgical candidates for primary cytoreductive surgery (as per their surgical gynecologic oncologist) and who have not yet undergone surgery.

⁃ Cohort 2: Patients with newly diagnosed ovarian cancers who are being considered for either primary surgery or neoadjuvant chemotherapy by their surgical gynecologic oncologist, and who require a laparoscopic procedure to determine their candidacy for surgery.

⁃ Cohort 3: Patients with recurrent ovarian cancer who are candidates for secondary cytoreduction, e.g. to confirm diagnosis of recurrent ovarian cancer and/or remove oligometastatic lesions.

⁃ Cohort 4: Patients with newly diagnosed ovarian cancers who have undergone neoadjuvant chemotherapy and are deemed surgical candidates for interval debulking surgery (as per their surgical gynecologic oncologist) and who have not yet undergone surgery.

• Participants must be 18 years of age or older.

• Patients must be deemed medically stable to undergo both percutaneous procedures and standard-of-care surgical procedures by their treating gynecologic oncologist and medical oncologist.

• Participants will undergo laboratory testing within 14 days\* prior to the microdevice placement.

‣ Patients must have absolute neutrophil count ≥ 1,500/mcL

⁃ Platelets ≥ 75,000/mcL

⁃ PT (INR) \< 1.5

⁃ PTT \< 1.5x control

⁃ Women of childbearing potential must have negative pregnancy test (urine or serum) \*\*Cohort 4 patients should undergo laboratory testing within 7 days prior to the microdevice placement

• Participants must be evaluated by a surgical gynecologic oncologist who will determine the clinically appropriate treatment strategy (primary surgery or neoadjuvant chemotherapy) based on clinical history and extent of disease. The patient's surgical and/or medical gynecologic oncologist must also confirm the patient's medical fitness to undergo an additional biopsy procedure and the indicated surgical procedure. The patient must have a plan to undergo surgery for clinical purposes.

• The following criteria must be met:

‣ Participants must have undergone an abdominal/pelvic CT scan that both assesses the extent of disease and identifies an area of tumor amenable to safe microdevice placement. CT scans with both oral and IV contrast media are preferred but not required.

⁃ CT scans performed at outside institutions are acceptable providing that the images are considered adequate to assess the stage of the disease and to assess the safety and feasibility of the placement of the microdevices and their retrieval during standard-of care surgery. CT scan must be completed within 4 weeks prior to the microdevice placement.

• Patient has sufficient volume of disease as measured by CT scan to allow implantation of the microdevice.

• Patient has sufficient volume of disease that removal of the lesion where the microdevice is placed will not potentially affect adequate tissue for diagnosis.

• A lesion can be selected where the microdevice is to be implanted that is

‣ Amenable to percutaneous placement

⁃ Amenable to removal at the time of surgery or laparoscopy. If patient is undergoing laparoscopy, the lesion must be able to be removed using a laparoscopic approach in a manner that would not significantly alter the procedure or affect patient safety, per opinion of the surgical oncologist.

• Patients must have the ability to understand and the willingness to sign a written informed consent document.

∙ Patients must be willing to undergo research-related genetic sequencing (somatic and germline) and data management, including the deposition of de-identified genetic sequencing data in NIH central data repositories.